CodeGenModule.cpp revision 4357a8291d759f6f9c36d3edeee8476d3eaf0804 
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 "CGDebugInfo.h"
16#include "CodeGenFunction.h"
17#include "CGCall.h"
18#include "CGObjCRuntime.h"
19#include "Mangle.h"
20#include "TargetInfo.h"
21#include "clang/CodeGen/CodeGenOptions.h"
22#include "clang/AST/ASTContext.h"
23#include "clang/AST/CharUnits.h"
24#include "clang/AST/DeclObjC.h"
25#include "clang/AST/DeclCXX.h"
26#include "clang/AST/RecordLayout.h"
27#include "clang/Basic/Builtins.h"
28#include "clang/Basic/Diagnostic.h"
29#include "clang/Basic/SourceManager.h"
30#include "clang/Basic/TargetInfo.h"
31#include "clang/Basic/ConvertUTF.h"
32#include "llvm/CallingConv.h"
33#include "llvm/Module.h"
34#include "llvm/Intrinsics.h"
35#include "llvm/LLVMContext.h"
36#include "llvm/ADT/Triple.h"
37#include "llvm/Target/TargetData.h"
38#include "llvm/Support/CallSite.h"
39#include "llvm/Support/ErrorHandling.h"
40using namespace clang;
41using namespace CodeGen;
42
43
44CodeGenModule::CodeGenModule(ASTContext &C, const CodeGenOptions &CGO,
45                             llvm::Module &M, const llvm::TargetData &TD,
46                             Diagnostic &diags)
47  : BlockModule(C, M, TD, Types, *this), Context(C),
48    Features(C.getLangOptions()), CodeGenOpts(CGO), TheModule(M),
49    TheTargetData(TD), TheTargetCodeGenInfo(0), Diags(diags),
50    Types(C, M, TD, getTargetCodeGenInfo().getABIInfo()),
51    MangleCtx(C, diags), VTables(*this), Runtime(0),
52    CFConstantStringClassRef(0),
53    VMContext(M.getContext()) {
54
55  if (!Features.ObjC1)
56    Runtime = 0;
57  else if (!Features.NeXTRuntime)
58    Runtime = CreateGNUObjCRuntime(*this);
59  else if (Features.ObjCNonFragileABI)
60    Runtime = CreateMacNonFragileABIObjCRuntime(*this);
61  else
62    Runtime = CreateMacObjCRuntime(*this);
63
64  // If debug info generation is enabled, create the CGDebugInfo object.
65  DebugInfo = CodeGenOpts.DebugInfo ? new CGDebugInfo(*this) : 0;
66}
67
68CodeGenModule::~CodeGenModule() {
69  delete Runtime;
70  delete DebugInfo;
71}
72
73void CodeGenModule::createObjCRuntime() {
74  if (!Features.NeXTRuntime)
75    Runtime = CreateGNUObjCRuntime(*this);
76  else if (Features.ObjCNonFragileABI)
77    Runtime = CreateMacNonFragileABIObjCRuntime(*this);
78  else
79    Runtime = CreateMacObjCRuntime(*this);
80}
81
82void CodeGenModule::Release() {
83  EmitDeferred();
84  EmitCXXGlobalInitFunc();
85  EmitCXXGlobalDtorFunc();
86  if (Runtime)
87    if (llvm::Function *ObjCInitFunction = Runtime->ModuleInitFunction())
88      AddGlobalCtor(ObjCInitFunction);
89  EmitCtorList(GlobalCtors, "llvm.global_ctors");
90  EmitCtorList(GlobalDtors, "llvm.global_dtors");
91  EmitAnnotations();
92  EmitLLVMUsed();
93}
94
95bool CodeGenModule::isTargetDarwin() const {
96  return getContext().Target.getTriple().getOS() == llvm::Triple::Darwin;
97}
98
99/// ErrorUnsupported - Print out an error that codegen doesn't support the
100/// specified stmt yet.
101void CodeGenModule::ErrorUnsupported(const Stmt *S, const char *Type,
102                                     bool OmitOnError) {
103  if (OmitOnError && getDiags().hasErrorOccurred())
104    return;
105  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
106                                               "cannot compile this %0 yet");
107  std::string Msg = Type;
108  getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID)
109    << Msg << S->getSourceRange();
110}
111
112/// ErrorUnsupported - Print out an error that codegen doesn't support the
113/// specified decl yet.
114void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type,
115                                     bool OmitOnError) {
116  if (OmitOnError && getDiags().hasErrorOccurred())
117    return;
118  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
119                                               "cannot compile this %0 yet");
120  std::string Msg = Type;
121  getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID) << Msg;
122}
123
124LangOptions::VisibilityMode
125CodeGenModule::getDeclVisibilityMode(const Decl *D) const {
126  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
127    if (VD->getStorageClass() == VarDecl::PrivateExtern)
128      return LangOptions::Hidden;
129
130  if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>()) {
131    switch (attr->getVisibility()) {
132    default: assert(0 && "Unknown visibility!");
133    case VisibilityAttr::DefaultVisibility:
134      return LangOptions::Default;
135    case VisibilityAttr::HiddenVisibility:
136      return LangOptions::Hidden;
137    case VisibilityAttr::ProtectedVisibility:
138      return LangOptions::Protected;
139    }
140  }
141
142  // This decl should have the same visibility as its parent.
143  if (const DeclContext *DC = D->getDeclContext())
144    return getDeclVisibilityMode(cast<Decl>(DC));
145
146  return getLangOptions().getVisibilityMode();
147}
148
149void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
150                                        const Decl *D) const {
151  // Internal definitions always have default visibility.
152  if (GV->hasLocalLinkage()) {
153    GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
154    return;
155  }
156
157  switch (getDeclVisibilityMode(D)) {
158  default: assert(0 && "Unknown visibility!");
159  case LangOptions::Default:
160    return GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
161  case LangOptions::Hidden:
162    return GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
163  case LangOptions::Protected:
164    return GV->setVisibility(llvm::GlobalValue::ProtectedVisibility);
165  }
166}
167
168void CodeGenModule::getMangledName(MangleBuffer &Buffer, GlobalDecl GD) {
169  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
170
171  if (const CXXConstructorDecl *D = dyn_cast<CXXConstructorDecl>(ND))
172    return getMangledCXXCtorName(Buffer, D, GD.getCtorType());
173  if (const CXXDestructorDecl *D = dyn_cast<CXXDestructorDecl>(ND))
174    return getMangledCXXDtorName(Buffer, D, GD.getDtorType());
175
176  return getMangledName(Buffer, ND);
177}
178
179/// \brief Retrieves the mangled name for the given declaration.
180///
181/// If the given declaration requires a mangled name, returns an
182/// const char* containing the mangled name.  Otherwise, returns
183/// the unmangled name.
184///
185void CodeGenModule::getMangledName(MangleBuffer &Buffer,
186                                   const NamedDecl *ND) {
187  if (!getMangleContext().shouldMangleDeclName(ND)) {
188    assert(ND->getIdentifier() && "Attempt to mangle unnamed decl.");
189    Buffer.setString(ND->getNameAsCString());
190    return;
191  }
192
193  getMangleContext().mangleName(ND, Buffer.getBuffer());
194}
195
196llvm::GlobalValue *CodeGenModule::GetGlobalValue(llvm::StringRef Name) {
197  return getModule().getNamedValue(Name);
198}
199
200/// AddGlobalCtor - Add a function to the list that will be called before
201/// main() runs.
202void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor, int Priority) {
203  // FIXME: Type coercion of void()* types.
204  GlobalCtors.push_back(std::make_pair(Ctor, Priority));
205}
206
207/// AddGlobalDtor - Add a function to the list that will be called
208/// when the module is unloaded.
209void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
210  // FIXME: Type coercion of void()* types.
211  GlobalDtors.push_back(std::make_pair(Dtor, Priority));
212}
213
214void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
215  // Ctor function type is void()*.
216  llvm::FunctionType* CtorFTy =
217    llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
218                            std::vector<const llvm::Type*>(),
219                            false);
220  llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
221
222  // Get the type of a ctor entry, { i32, void ()* }.
223  llvm::StructType* CtorStructTy =
224    llvm::StructType::get(VMContext, llvm::Type::getInt32Ty(VMContext),
225                          llvm::PointerType::getUnqual(CtorFTy), NULL);
226
227  // Construct the constructor and destructor arrays.
228  std::vector<llvm::Constant*> Ctors;
229  for (CtorList::const_iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
230    std::vector<llvm::Constant*> S;
231    S.push_back(llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
232                I->second, false));
233    S.push_back(llvm::ConstantExpr::getBitCast(I->first, CtorPFTy));
234    Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
235  }
236
237  if (!Ctors.empty()) {
238    llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
239    new llvm::GlobalVariable(TheModule, AT, false,
240                             llvm::GlobalValue::AppendingLinkage,
241                             llvm::ConstantArray::get(AT, Ctors),
242                             GlobalName);
243  }
244}
245
246void CodeGenModule::EmitAnnotations() {
247  if (Annotations.empty())
248    return;
249
250  // Create a new global variable for the ConstantStruct in the Module.
251  llvm::Constant *Array =
252  llvm::ConstantArray::get(llvm::ArrayType::get(Annotations[0]->getType(),
253                                                Annotations.size()),
254                           Annotations);
255  llvm::GlobalValue *gv =
256  new llvm::GlobalVariable(TheModule, Array->getType(), false,
257                           llvm::GlobalValue::AppendingLinkage, Array,
258                           "llvm.global.annotations");
259  gv->setSection("llvm.metadata");
260}
261
262static CodeGenModule::GVALinkage
263GetLinkageForFunction(ASTContext &Context, const FunctionDecl *FD,
264                      const LangOptions &Features) {
265  CodeGenModule::GVALinkage External = CodeGenModule::GVA_StrongExternal;
266
267  Linkage L = FD->getLinkage();
268  if (L == ExternalLinkage && Context.getLangOptions().CPlusPlus &&
269      FD->getType()->getLinkage() == UniqueExternalLinkage)
270    L = UniqueExternalLinkage;
271
272  switch (L) {
273  case NoLinkage:
274  case InternalLinkage:
275  case UniqueExternalLinkage:
276    return CodeGenModule::GVA_Internal;
277
278  case ExternalLinkage:
279    switch (FD->getTemplateSpecializationKind()) {
280    case TSK_Undeclared:
281    case TSK_ExplicitSpecialization:
282      External = CodeGenModule::GVA_StrongExternal;
283      break;
284
285    case TSK_ExplicitInstantiationDefinition:
286      return CodeGenModule::GVA_ExplicitTemplateInstantiation;
287
288    case TSK_ExplicitInstantiationDeclaration:
289    case TSK_ImplicitInstantiation:
290      External = CodeGenModule::GVA_TemplateInstantiation;
291      break;
292    }
293  }
294
295  if (!FD->isInlined())
296    return External;
297
298  if (!Features.CPlusPlus || FD->hasAttr<GNUInlineAttr>()) {
299    // GNU or C99 inline semantics. Determine whether this symbol should be
300    // externally visible.
301    if (FD->isInlineDefinitionExternallyVisible())
302      return External;
303
304    // C99 inline semantics, where the symbol is not externally visible.
305    return CodeGenModule::GVA_C99Inline;
306  }
307
308  // C++0x [temp.explicit]p9:
309  //   [ Note: The intent is that an inline function that is the subject of
310  //   an explicit instantiation declaration will still be implicitly
311  //   instantiated when used so that the body can be considered for
312  //   inlining, but that no out-of-line copy of the inline function would be
313  //   generated in the translation unit. -- end note ]
314  if (FD->getTemplateSpecializationKind()
315                                       == TSK_ExplicitInstantiationDeclaration)
316    return CodeGenModule::GVA_C99Inline;
317
318  return CodeGenModule::GVA_CXXInline;
319}
320
321llvm::GlobalValue::LinkageTypes
322CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
323  GVALinkage Linkage = GetLinkageForFunction(getContext(), D, Features);
324
325  if (Linkage == GVA_Internal) {
326    return llvm::Function::InternalLinkage;
327  } else if (D->hasAttr<DLLExportAttr>()) {
328    return llvm::Function::DLLExportLinkage;
329  } else if (D->hasAttr<WeakAttr>()) {
330    return llvm::Function::WeakAnyLinkage;
331  } else if (Linkage == GVA_C99Inline) {
332    // In C99 mode, 'inline' functions are guaranteed to have a strong
333    // definition somewhere else, so we can use available_externally linkage.
334    return llvm::Function::AvailableExternallyLinkage;
335  } else if (Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation) {
336    // In C++, the compiler has to emit a definition in every translation unit
337    // that references the function.  We should use linkonce_odr because
338    // a) if all references in this translation unit are optimized away, we
339    // don't need to codegen it.  b) if the function persists, it needs to be
340    // merged with other definitions. c) C++ has the ODR, so we know the
341    // definition is dependable.
342    return llvm::Function::LinkOnceODRLinkage;
343  } else if (Linkage == GVA_ExplicitTemplateInstantiation) {
344    // An explicit instantiation of a template has weak linkage, since
345    // explicit instantiations can occur in multiple translation units
346    // and must all be equivalent. However, we are not allowed to
347    // throw away these explicit instantiations.
348    return llvm::Function::WeakODRLinkage;
349  } else {
350    assert(Linkage == GVA_StrongExternal);
351    // Otherwise, we have strong external linkage.
352    return llvm::Function::ExternalLinkage;
353  }
354}
355
356
357/// SetFunctionDefinitionAttributes - Set attributes for a global.
358///
359/// FIXME: This is currently only done for aliases and functions, but not for
360/// variables (these details are set in EmitGlobalVarDefinition for variables).
361void CodeGenModule::SetFunctionDefinitionAttributes(const FunctionDecl *D,
362                                                    llvm::GlobalValue *GV) {
363  GV->setLinkage(getFunctionLinkage(D));
364  SetCommonAttributes(D, GV);
365}
366
367void CodeGenModule::SetLLVMFunctionAttributes(const Decl *D,
368                                              const CGFunctionInfo &Info,
369                                              llvm::Function *F) {
370  unsigned CallingConv;
371  AttributeListType AttributeList;
372  ConstructAttributeList(Info, D, AttributeList, CallingConv);
373  F->setAttributes(llvm::AttrListPtr::get(AttributeList.begin(),
374                                          AttributeList.size()));
375  F->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
376}
377
378void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
379                                                           llvm::Function *F) {
380  if (!Features.Exceptions && !Features.ObjCNonFragileABI)
381    F->addFnAttr(llvm::Attribute::NoUnwind);
382
383  if (D->hasAttr<AlwaysInlineAttr>())
384    F->addFnAttr(llvm::Attribute::AlwaysInline);
385
386  if (D->hasAttr<NoInlineAttr>())
387    F->addFnAttr(llvm::Attribute::NoInline);
388
389  if (Features.getStackProtectorMode() == LangOptions::SSPOn)
390    F->addFnAttr(llvm::Attribute::StackProtect);
391  else if (Features.getStackProtectorMode() == LangOptions::SSPReq)
392    F->addFnAttr(llvm::Attribute::StackProtectReq);
393
394  if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) {
395    unsigned width = Context.Target.getCharWidth();
396    F->setAlignment(AA->getAlignment() / width);
397    while ((AA = AA->getNext<AlignedAttr>()))
398      F->setAlignment(std::max(F->getAlignment(), AA->getAlignment() / width));
399  }
400  // C++ ABI requires 2-byte alignment for member functions.
401  if (F->getAlignment() < 2 && isa<CXXMethodDecl>(D))
402    F->setAlignment(2);
403}
404
405void CodeGenModule::SetCommonAttributes(const Decl *D,
406                                        llvm::GlobalValue *GV) {
407  setGlobalVisibility(GV, D);
408
409  if (D->hasAttr<UsedAttr>())
410    AddUsedGlobal(GV);
411
412  if (const SectionAttr *SA = D->getAttr<SectionAttr>())
413    GV->setSection(SA->getName());
414
415  getTargetCodeGenInfo().SetTargetAttributes(D, GV, *this);
416}
417
418void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
419                                                  llvm::Function *F,
420                                                  const CGFunctionInfo &FI) {
421  SetLLVMFunctionAttributes(D, FI, F);
422  SetLLVMFunctionAttributesForDefinition(D, F);
423
424  F->setLinkage(llvm::Function::InternalLinkage);
425
426  SetCommonAttributes(D, F);
427}
428
429void CodeGenModule::SetFunctionAttributes(GlobalDecl GD,
430                                          llvm::Function *F,
431                                          bool IsIncompleteFunction) {
432  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
433
434  if (!IsIncompleteFunction)
435    SetLLVMFunctionAttributes(FD, getTypes().getFunctionInfo(GD), F);
436
437  // Only a few attributes are set on declarations; these may later be
438  // overridden by a definition.
439
440  if (FD->hasAttr<DLLImportAttr>()) {
441    F->setLinkage(llvm::Function::DLLImportLinkage);
442  } else if (FD->hasAttr<WeakAttr>() ||
443             FD->hasAttr<WeakImportAttr>()) {
444    // "extern_weak" is overloaded in LLVM; we probably should have
445    // separate linkage types for this.
446    F->setLinkage(llvm::Function::ExternalWeakLinkage);
447  } else {
448    F->setLinkage(llvm::Function::ExternalLinkage);
449  }
450
451  if (const SectionAttr *SA = FD->getAttr<SectionAttr>())
452    F->setSection(SA->getName());
453}
454
455void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
456  assert(!GV->isDeclaration() &&
457         "Only globals with definition can force usage.");
458  LLVMUsed.push_back(GV);
459}
460
461void CodeGenModule::EmitLLVMUsed() {
462  // Don't create llvm.used if there is no need.
463  if (LLVMUsed.empty())
464    return;
465
466  const llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(VMContext);
467
468  // Convert LLVMUsed to what ConstantArray needs.
469  std::vector<llvm::Constant*> UsedArray;
470  UsedArray.resize(LLVMUsed.size());
471  for (unsigned i = 0, e = LLVMUsed.size(); i != e; ++i) {
472    UsedArray[i] =
473     llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*LLVMUsed[i]),
474                                      i8PTy);
475  }
476
477  if (UsedArray.empty())
478    return;
479  llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, UsedArray.size());
480
481  llvm::GlobalVariable *GV =
482    new llvm::GlobalVariable(getModule(), ATy, false,
483                             llvm::GlobalValue::AppendingLinkage,
484                             llvm::ConstantArray::get(ATy, UsedArray),
485                             "llvm.used");
486
487  GV->setSection("llvm.metadata");
488}
489
490void CodeGenModule::EmitDeferred() {
491  // Emit code for any potentially referenced deferred decls.  Since a
492  // previously unused static decl may become used during the generation of code
493  // for a static function, iterate until no  changes are made.
494
495  while (!DeferredDeclsToEmit.empty() || !DeferredVtables.empty()) {
496    if (!DeferredVtables.empty()) {
497      const CXXRecordDecl *RD = DeferredVtables.back();
498      DeferredVtables.pop_back();
499      getVTables().GenerateClassData(getVtableLinkage(RD), RD);
500      continue;
501    }
502
503    GlobalDecl D = DeferredDeclsToEmit.back();
504    DeferredDeclsToEmit.pop_back();
505
506    // Look it up to see if it was defined with a stronger definition (e.g. an
507    // extern inline function with a strong function redefinition).  If so,
508    // just ignore the deferred decl.
509    MangleBuffer Name;
510    getMangledName(Name, D);
511    llvm::GlobalValue *CGRef = GetGlobalValue(Name);
512    assert(CGRef && "Deferred decl wasn't referenced?");
513
514    if (!CGRef->isDeclaration())
515      continue;
516
517    // Otherwise, emit the definition and move on to the next one.
518    EmitGlobalDefinition(D);
519  }
520}
521
522/// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
523/// annotation information for a given GlobalValue.  The annotation struct is
524/// {i8 *, i8 *, i8 *, i32}.  The first field is a constant expression, the
525/// GlobalValue being annotated.  The second field is the constant string
526/// created from the AnnotateAttr's annotation.  The third field is a constant
527/// string containing the name of the translation unit.  The fourth field is
528/// the line number in the file of the annotated value declaration.
529///
530/// FIXME: this does not unique the annotation string constants, as llvm-gcc
531///        appears to.
532///
533llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
534                                                const AnnotateAttr *AA,
535                                                unsigned LineNo) {
536  llvm::Module *M = &getModule();
537
538  // get [N x i8] constants for the annotation string, and the filename string
539  // which are the 2nd and 3rd elements of the global annotation structure.
540  const llvm::Type *SBP = llvm::Type::getInt8PtrTy(VMContext);
541  llvm::Constant *anno = llvm::ConstantArray::get(VMContext,
542                                                  AA->getAnnotation(), true);
543  llvm::Constant *unit = llvm::ConstantArray::get(VMContext,
544                                                  M->getModuleIdentifier(),
545                                                  true);
546
547  // Get the two global values corresponding to the ConstantArrays we just
548  // created to hold the bytes of the strings.
549  llvm::GlobalValue *annoGV =
550    new llvm::GlobalVariable(*M, anno->getType(), false,
551                             llvm::GlobalValue::PrivateLinkage, anno,
552                             GV->getName());
553  // translation unit name string, emitted into the llvm.metadata section.
554  llvm::GlobalValue *unitGV =
555    new llvm::GlobalVariable(*M, unit->getType(), false,
556                             llvm::GlobalValue::PrivateLinkage, unit,
557                             ".str");
558
559  // Create the ConstantStruct for the global annotation.
560  llvm::Constant *Fields[4] = {
561    llvm::ConstantExpr::getBitCast(GV, SBP),
562    llvm::ConstantExpr::getBitCast(annoGV, SBP),
563    llvm::ConstantExpr::getBitCast(unitGV, SBP),
564    llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), LineNo)
565  };
566  return llvm::ConstantStruct::get(VMContext, Fields, 4, false);
567}
568
569bool CodeGenModule::MayDeferGeneration(const ValueDecl *Global) {
570  // Never defer when EmitAllDecls is specified or the decl has
571  // attribute used.
572  if (Features.EmitAllDecls || Global->hasAttr<UsedAttr>())
573    return false;
574
575  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
576    // Constructors and destructors should never be deferred.
577    if (FD->hasAttr<ConstructorAttr>() ||
578        FD->hasAttr<DestructorAttr>())
579      return false;
580
581    // The key function for a class must never be deferred.
582    if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Global)) {
583      const CXXRecordDecl *RD = MD->getParent();
584      if (MD->isOutOfLine() && RD->isDynamicClass()) {
585        const CXXMethodDecl *KeyFunction = getContext().getKeyFunction(RD);
586        if (KeyFunction &&
587            KeyFunction->getCanonicalDecl() == MD->getCanonicalDecl())
588          return false;
589      }
590    }
591
592    GVALinkage Linkage = GetLinkageForFunction(getContext(), FD, Features);
593
594    // static, static inline, always_inline, and extern inline functions can
595    // always be deferred.  Normal inline functions can be deferred in C99/C++.
596    // Implicit template instantiations can also be deferred in C++.
597    if (Linkage == GVA_Internal || Linkage == GVA_C99Inline ||
598        Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation)
599      return true;
600    return false;
601  }
602
603  const VarDecl *VD = cast<VarDecl>(Global);
604  assert(VD->isFileVarDecl() && "Invalid decl");
605
606  // We never want to defer structs that have non-trivial constructors or
607  // destructors.
608
609  // FIXME: Handle references.
610  if (const RecordType *RT = VD->getType()->getAs<RecordType>()) {
611    if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
612      if (!RD->hasTrivialConstructor() || !RD->hasTrivialDestructor())
613        return false;
614    }
615  }
616
617  // Static data may be deferred, but out-of-line static data members
618  // cannot be.
619  Linkage L = VD->getLinkage();
620  if (L == ExternalLinkage && getContext().getLangOptions().CPlusPlus &&
621      VD->getType()->getLinkage() == UniqueExternalLinkage)
622    L = UniqueExternalLinkage;
623
624  switch (L) {
625  case NoLinkage:
626  case InternalLinkage:
627  case UniqueExternalLinkage:
628    // Initializer has side effects?
629    if (VD->getInit() && VD->getInit()->HasSideEffects(Context))
630      return false;
631    return !(VD->isStaticDataMember() && VD->isOutOfLine());
632
633  case ExternalLinkage:
634    break;
635  }
636
637  return false;
638}
639
640llvm::Constant *CodeGenModule::GetWeakRefReference(const ValueDecl *VD) {
641  const AliasAttr *AA = VD->getAttr<AliasAttr>();
642  assert(AA && "No alias?");
643
644  const llvm::Type *DeclTy = getTypes().ConvertTypeForMem(VD->getType());
645
646  // See if there is already something with the target's name in the module.
647  llvm::GlobalValue *Entry = GetGlobalValue(AA->getAliasee());
648
649  llvm::Constant *Aliasee;
650  if (isa<llvm::FunctionType>(DeclTy))
651    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl());
652  else
653    Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
654                                    llvm::PointerType::getUnqual(DeclTy), 0);
655  if (!Entry) {
656    llvm::GlobalValue* F = cast<llvm::GlobalValue>(Aliasee);
657    F->setLinkage(llvm::Function::ExternalWeakLinkage);
658    WeakRefReferences.insert(F);
659  }
660
661  return Aliasee;
662}
663
664void CodeGenModule::EmitGlobal(GlobalDecl GD) {
665  const ValueDecl *Global = cast<ValueDecl>(GD.getDecl());
666
667  // Weak references don't produce any output by themselves.
668  if (Global->hasAttr<WeakRefAttr>())
669    return;
670
671  // If this is an alias definition (which otherwise looks like a declaration)
672  // emit it now.
673  if (Global->hasAttr<AliasAttr>())
674    return EmitAliasDefinition(GD);
675
676  // Ignore declarations, they will be emitted on their first use.
677  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
678    // Forward declarations are emitted lazily on first use.
679    if (!FD->isThisDeclarationADefinition())
680      return;
681  } else {
682    const VarDecl *VD = cast<VarDecl>(Global);
683    assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
684
685    if (VD->isThisDeclarationADefinition() != VarDecl::Definition)
686      return;
687  }
688
689  // Defer code generation when possible if this is a static definition, inline
690  // function etc.  These we only want to emit if they are used.
691  if (!MayDeferGeneration(Global)) {
692    // Emit the definition if it can't be deferred.
693    EmitGlobalDefinition(GD);
694    return;
695  }
696
697  // If the value has already been used, add it directly to the
698  // DeferredDeclsToEmit list.
699  MangleBuffer MangledName;
700  getMangledName(MangledName, GD);
701  if (GetGlobalValue(MangledName))
702    DeferredDeclsToEmit.push_back(GD);
703  else {
704    // Otherwise, remember that we saw a deferred decl with this name.  The
705    // first use of the mangled name will cause it to move into
706    // DeferredDeclsToEmit.
707    DeferredDecls[MangledName] = GD;
708  }
709}
710
711void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD) {
712  const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
713
714  PrettyStackTraceDecl CrashInfo((ValueDecl *)D, D->getLocation(),
715                                 Context.getSourceManager(),
716                                 "Generating code for declaration");
717
718  if (isa<CXXMethodDecl>(D))
719    getVTables().EmitVTableRelatedData(GD);
720
721  if (isa<FunctionDecl>(D))
722    return EmitGlobalFunctionDefinition(GD);
723
724  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
725    return EmitGlobalVarDefinition(VD);
726
727  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
728    return EmitCXXConstructor(CD, GD.getCtorType());
729
730  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(D))
731    return EmitCXXDestructor(DD, GD.getDtorType());
732
733  assert(0 && "Invalid argument to EmitGlobalDefinition()");
734}
735
736/// GetOrCreateLLVMFunction - If the specified mangled name is not in the
737/// module, create and return an llvm Function with the specified type. If there
738/// is something in the module with the specified name, return it potentially
739/// bitcasted to the right type.
740///
741/// If D is non-null, it specifies a decl that correspond to this.  This is used
742/// to set the attributes on the function when it is first created.
743llvm::Constant *
744CodeGenModule::GetOrCreateLLVMFunction(llvm::StringRef MangledName,
745                                       const llvm::Type *Ty,
746                                       GlobalDecl D) {
747  // Lookup the entry, lazily creating it if necessary.
748  llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
749  if (Entry) {
750    if (WeakRefReferences.count(Entry)) {
751      const FunctionDecl *FD = cast_or_null<FunctionDecl>(D.getDecl());
752      if (FD && !FD->hasAttr<WeakAttr>())
753        Entry->setLinkage(llvm::Function::ExternalLinkage);
754
755      WeakRefReferences.erase(Entry);
756    }
757
758    if (Entry->getType()->getElementType() == Ty)
759      return Entry;
760
761    // Make sure the result is of the correct type.
762    const llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
763    return llvm::ConstantExpr::getBitCast(Entry, PTy);
764  }
765
766  // This function doesn't have a complete type (for example, the return
767  // type is an incomplete struct). Use a fake type instead, and make
768  // sure not to try to set attributes.
769  bool IsIncompleteFunction = false;
770  if (!isa<llvm::FunctionType>(Ty)) {
771    Ty = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
772                                 std::vector<const llvm::Type*>(), false);
773    IsIncompleteFunction = true;
774  }
775  llvm::Function *F = llvm::Function::Create(cast<llvm::FunctionType>(Ty),
776                                             llvm::Function::ExternalLinkage,
777                                             MangledName, &getModule());
778  assert(F->getName() == MangledName && "name was uniqued!");
779  if (D.getDecl())
780    SetFunctionAttributes(D, F, IsIncompleteFunction);
781
782  // This is the first use or definition of a mangled name.  If there is a
783  // deferred decl with this name, remember that we need to emit it at the end
784  // of the file.
785  llvm::StringMap<GlobalDecl>::iterator DDI = DeferredDecls.find(MangledName);
786  if (DDI != DeferredDecls.end()) {
787    // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
788    // list, and remove it from DeferredDecls (since we don't need it anymore).
789    DeferredDeclsToEmit.push_back(DDI->second);
790    DeferredDecls.erase(DDI);
791  } else if (const FunctionDecl *FD = cast_or_null<FunctionDecl>(D.getDecl())) {
792    // If this the first reference to a C++ inline function in a class, queue up
793    // the deferred function body for emission.  These are not seen as
794    // top-level declarations.
795    if (FD->isThisDeclarationADefinition() && MayDeferGeneration(FD))
796      DeferredDeclsToEmit.push_back(D);
797    // A called constructor which has no definition or declaration need be
798    // synthesized.
799    else if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
800      if (CD->isImplicit()) {
801        assert(CD->isUsed() && "Sema doesn't consider constructor as used.");
802        DeferredDeclsToEmit.push_back(D);
803      }
804    } else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD)) {
805      if (DD->isImplicit()) {
806        assert(DD->isUsed() && "Sema doesn't consider destructor as used.");
807        DeferredDeclsToEmit.push_back(D);
808      }
809    } else if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
810      if (MD->isCopyAssignment() && MD->isImplicit()) {
811        assert(MD->isUsed() && "Sema doesn't consider CopyAssignment as used.");
812        DeferredDeclsToEmit.push_back(D);
813      }
814    }
815  }
816
817  return F;
818}
819
820/// GetAddrOfFunction - Return the address of the given function.  If Ty is
821/// non-null, then this function will use the specified type if it has to
822/// create it (this occurs when we see a definition of the function).
823llvm::Constant *CodeGenModule::GetAddrOfFunction(GlobalDecl GD,
824                                                 const llvm::Type *Ty) {
825  // If there was no specific requested type, just convert it now.
826  if (!Ty)
827    Ty = getTypes().ConvertType(cast<ValueDecl>(GD.getDecl())->getType());
828  MangleBuffer MangledName;
829  getMangledName(MangledName, GD);
830  return GetOrCreateLLVMFunction(MangledName, Ty, GD);
831}
832
833/// CreateRuntimeFunction - Create a new runtime function with the specified
834/// type and name.
835llvm::Constant *
836CodeGenModule::CreateRuntimeFunction(const llvm::FunctionType *FTy,
837                                     llvm::StringRef Name) {
838  return GetOrCreateLLVMFunction(Name, FTy, GlobalDecl());
839}
840
841static bool DeclIsConstantGlobal(ASTContext &Context, const VarDecl *D) {
842  if (!D->getType().isConstant(Context) && !D->getType()->isReferenceType())
843    return false;
844  if (Context.getLangOptions().CPlusPlus &&
845      Context.getBaseElementType(D->getType())->getAs<RecordType>()) {
846    // FIXME: We should do something fancier here!
847    return false;
848  }
849  return true;
850}
851
852/// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
853/// create and return an llvm GlobalVariable with the specified type.  If there
854/// is something in the module with the specified name, return it potentially
855/// bitcasted to the right type.
856///
857/// If D is non-null, it specifies a decl that correspond to this.  This is used
858/// to set the attributes on the global when it is first created.
859llvm::Constant *
860CodeGenModule::GetOrCreateLLVMGlobal(llvm::StringRef MangledName,
861                                     const llvm::PointerType *Ty,
862                                     const VarDecl *D) {
863  // Lookup the entry, lazily creating it if necessary.
864  llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
865  if (Entry) {
866    if (WeakRefReferences.count(Entry)) {
867      if (D && !D->hasAttr<WeakAttr>())
868        Entry->setLinkage(llvm::Function::ExternalLinkage);
869
870      WeakRefReferences.erase(Entry);
871    }
872
873    if (Entry->getType() == Ty)
874      return Entry;
875
876    // Make sure the result is of the correct type.
877    return llvm::ConstantExpr::getBitCast(Entry, Ty);
878  }
879
880  // This is the first use or definition of a mangled name.  If there is a
881  // deferred decl with this name, remember that we need to emit it at the end
882  // of the file.
883  llvm::StringMap<GlobalDecl>::iterator DDI = DeferredDecls.find(MangledName);
884  if (DDI != DeferredDecls.end()) {
885    // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
886    // list, and remove it from DeferredDecls (since we don't need it anymore).
887    DeferredDeclsToEmit.push_back(DDI->second);
888    DeferredDecls.erase(DDI);
889  }
890
891  llvm::GlobalVariable *GV =
892    new llvm::GlobalVariable(getModule(), Ty->getElementType(), false,
893                             llvm::GlobalValue::ExternalLinkage,
894                             0, MangledName, 0,
895                             false, Ty->getAddressSpace());
896
897  // Handle things which are present even on external declarations.
898  if (D) {
899    // FIXME: This code is overly simple and should be merged with other global
900    // handling.
901    GV->setConstant(DeclIsConstantGlobal(Context, D));
902
903    // FIXME: Merge with other attribute handling code.
904    if (D->getStorageClass() == VarDecl::PrivateExtern)
905      GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
906
907    if (D->hasAttr<WeakAttr>() ||
908        D->hasAttr<WeakImportAttr>())
909      GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
910
911    GV->setThreadLocal(D->isThreadSpecified());
912  }
913
914  return GV;
915}
916
917
918/// GetAddrOfGlobalVar - Return the llvm::Constant for the address of the
919/// given global variable.  If Ty is non-null and if the global doesn't exist,
920/// then it will be greated with the specified type instead of whatever the
921/// normal requested type would be.
922llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D,
923                                                  const llvm::Type *Ty) {
924  assert(D->hasGlobalStorage() && "Not a global variable");
925  QualType ASTTy = D->getType();
926  if (Ty == 0)
927    Ty = getTypes().ConvertTypeForMem(ASTTy);
928
929  const llvm::PointerType *PTy =
930    llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
931
932  MangleBuffer MangledName;
933  getMangledName(MangledName, D);
934  return GetOrCreateLLVMGlobal(MangledName, PTy, D);
935}
936
937/// CreateRuntimeVariable - Create a new runtime global variable with the
938/// specified type and name.
939llvm::Constant *
940CodeGenModule::CreateRuntimeVariable(const llvm::Type *Ty,
941                                     llvm::StringRef Name) {
942  return GetOrCreateLLVMGlobal(Name, llvm::PointerType::getUnqual(Ty), 0);
943}
944
945void CodeGenModule::EmitTentativeDefinition(const VarDecl *D) {
946  assert(!D->getInit() && "Cannot emit definite definitions here!");
947
948  if (MayDeferGeneration(D)) {
949    // If we have not seen a reference to this variable yet, place it
950    // into the deferred declarations table to be emitted if needed
951    // later.
952    MangleBuffer MangledName;
953    getMangledName(MangledName, D);
954    if (!GetGlobalValue(MangledName)) {
955      DeferredDecls[MangledName] = D;
956      return;
957    }
958  }
959
960  // The tentative definition is the only definition.
961  EmitGlobalVarDefinition(D);
962}
963
964llvm::GlobalVariable::LinkageTypes
965CodeGenModule::getVtableLinkage(const CXXRecordDecl *RD) {
966  if (RD->isInAnonymousNamespace() || !RD->hasLinkage())
967    return llvm::GlobalVariable::InternalLinkage;
968
969  if (const CXXMethodDecl *KeyFunction
970                                    = RD->getASTContext().getKeyFunction(RD)) {
971    // If this class has a key function, use that to determine the linkage of
972    // the vtable.
973    const FunctionDecl *Def = 0;
974    if (KeyFunction->getBody(Def))
975      KeyFunction = cast<CXXMethodDecl>(Def);
976
977    switch (KeyFunction->getTemplateSpecializationKind()) {
978      case TSK_Undeclared:
979      case TSK_ExplicitSpecialization:
980        if (KeyFunction->isInlined())
981          return llvm::GlobalVariable::WeakODRLinkage;
982
983        return llvm::GlobalVariable::ExternalLinkage;
984
985      case TSK_ImplicitInstantiation:
986      case TSK_ExplicitInstantiationDefinition:
987        return llvm::GlobalVariable::WeakODRLinkage;
988
989      case TSK_ExplicitInstantiationDeclaration:
990        // FIXME: Use available_externally linkage. However, this currently
991        // breaks LLVM's build due to undefined symbols.
992        //      return llvm::GlobalVariable::AvailableExternallyLinkage;
993        return llvm::GlobalVariable::WeakODRLinkage;
994    }
995  }
996
997  switch (RD->getTemplateSpecializationKind()) {
998  case TSK_Undeclared:
999  case TSK_ExplicitSpecialization:
1000  case TSK_ImplicitInstantiation:
1001  case TSK_ExplicitInstantiationDefinition:
1002    return llvm::GlobalVariable::WeakODRLinkage;
1003
1004  case TSK_ExplicitInstantiationDeclaration:
1005    // FIXME: Use available_externally linkage. However, this currently
1006    // breaks LLVM's build due to undefined symbols.
1007    //   return llvm::GlobalVariable::AvailableExternallyLinkage;
1008    return llvm::GlobalVariable::WeakODRLinkage;
1009  }
1010
1011  // Silence GCC warning.
1012  return llvm::GlobalVariable::WeakODRLinkage;
1013}
1014
1015static CodeGenModule::GVALinkage
1016GetLinkageForVariable(ASTContext &Context, const VarDecl *VD) {
1017  // If this is a static data member, compute the kind of template
1018  // specialization. Otherwise, this variable is not part of a
1019  // template.
1020  TemplateSpecializationKind TSK = TSK_Undeclared;
1021  if (VD->isStaticDataMember())
1022    TSK = VD->getTemplateSpecializationKind();
1023
1024  Linkage L = VD->getLinkage();
1025  if (L == ExternalLinkage && Context.getLangOptions().CPlusPlus &&
1026      VD->getType()->getLinkage() == UniqueExternalLinkage)
1027    L = UniqueExternalLinkage;
1028
1029  switch (L) {
1030  case NoLinkage:
1031  case InternalLinkage:
1032  case UniqueExternalLinkage:
1033    return CodeGenModule::GVA_Internal;
1034
1035  case ExternalLinkage:
1036    switch (TSK) {
1037    case TSK_Undeclared:
1038    case TSK_ExplicitSpecialization:
1039      return CodeGenModule::GVA_StrongExternal;
1040
1041    case TSK_ExplicitInstantiationDeclaration:
1042      llvm_unreachable("Variable should not be instantiated");
1043      // Fall through to treat this like any other instantiation.
1044
1045    case TSK_ExplicitInstantiationDefinition:
1046      return CodeGenModule::GVA_ExplicitTemplateInstantiation;
1047
1048    case TSK_ImplicitInstantiation:
1049      return CodeGenModule::GVA_TemplateInstantiation;
1050    }
1051  }
1052
1053  return CodeGenModule::GVA_StrongExternal;
1054}
1055
1056CharUnits CodeGenModule::GetTargetTypeStoreSize(const llvm::Type *Ty) const {
1057    return CharUnits::fromQuantity(
1058      TheTargetData.getTypeStoreSizeInBits(Ty) / Context.getCharWidth());
1059}
1060
1061void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
1062  llvm::Constant *Init = 0;
1063  QualType ASTTy = D->getType();
1064  bool NonConstInit = false;
1065
1066  const Expr *InitExpr = D->getAnyInitializer();
1067
1068  if (!InitExpr) {
1069    // This is a tentative definition; tentative definitions are
1070    // implicitly initialized with { 0 }.
1071    //
1072    // Note that tentative definitions are only emitted at the end of
1073    // a translation unit, so they should never have incomplete
1074    // type. In addition, EmitTentativeDefinition makes sure that we
1075    // never attempt to emit a tentative definition if a real one
1076    // exists. A use may still exists, however, so we still may need
1077    // to do a RAUW.
1078    assert(!ASTTy->isIncompleteType() && "Unexpected incomplete type");
1079    Init = EmitNullConstant(D->getType());
1080  } else {
1081    Init = EmitConstantExpr(InitExpr, D->getType());
1082
1083    if (!Init) {
1084      QualType T = InitExpr->getType();
1085      if (getLangOptions().CPlusPlus) {
1086        EmitCXXGlobalVarDeclInitFunc(D);
1087        Init = EmitNullConstant(T);
1088        NonConstInit = true;
1089      } else {
1090        ErrorUnsupported(D, "static initializer");
1091        Init = llvm::UndefValue::get(getTypes().ConvertType(T));
1092      }
1093    }
1094  }
1095
1096  const llvm::Type* InitType = Init->getType();
1097  llvm::Constant *Entry = GetAddrOfGlobalVar(D, InitType);
1098
1099  // Strip off a bitcast if we got one back.
1100  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
1101    assert(CE->getOpcode() == llvm::Instruction::BitCast ||
1102           // all zero index gep.
1103           CE->getOpcode() == llvm::Instruction::GetElementPtr);
1104    Entry = CE->getOperand(0);
1105  }
1106
1107  // Entry is now either a Function or GlobalVariable.
1108  llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Entry);
1109
1110  // We have a definition after a declaration with the wrong type.
1111  // We must make a new GlobalVariable* and update everything that used OldGV
1112  // (a declaration or tentative definition) with the new GlobalVariable*
1113  // (which will be a definition).
1114  //
1115  // This happens if there is a prototype for a global (e.g.
1116  // "extern int x[];") and then a definition of a different type (e.g.
1117  // "int x[10];"). This also happens when an initializer has a different type
1118  // from the type of the global (this happens with unions).
1119  if (GV == 0 ||
1120      GV->getType()->getElementType() != InitType ||
1121      GV->getType()->getAddressSpace() != ASTTy.getAddressSpace()) {
1122
1123    // Move the old entry aside so that we'll create a new one.
1124    Entry->setName(llvm::StringRef());
1125
1126    // Make a new global with the correct type, this is now guaranteed to work.
1127    GV = cast<llvm::GlobalVariable>(GetAddrOfGlobalVar(D, InitType));
1128
1129    // Replace all uses of the old global with the new global
1130    llvm::Constant *NewPtrForOldDecl =
1131        llvm::ConstantExpr::getBitCast(GV, Entry->getType());
1132    Entry->replaceAllUsesWith(NewPtrForOldDecl);
1133
1134    // Erase the old global, since it is no longer used.
1135    cast<llvm::GlobalValue>(Entry)->eraseFromParent();
1136  }
1137
1138  if (const AnnotateAttr *AA = D->getAttr<AnnotateAttr>()) {
1139    SourceManager &SM = Context.getSourceManager();
1140    AddAnnotation(EmitAnnotateAttr(GV, AA,
1141                              SM.getInstantiationLineNumber(D->getLocation())));
1142  }
1143
1144  GV->setInitializer(Init);
1145
1146  // If it is safe to mark the global 'constant', do so now.
1147  GV->setConstant(false);
1148  if (!NonConstInit && DeclIsConstantGlobal(Context, D))
1149    GV->setConstant(true);
1150
1151  GV->setAlignment(getContext().getDeclAlign(D).getQuantity());
1152
1153  // Set the llvm linkage type as appropriate.
1154  GVALinkage Linkage = GetLinkageForVariable(getContext(), D);
1155  if (Linkage == GVA_Internal)
1156    GV->setLinkage(llvm::Function::InternalLinkage);
1157  else if (D->hasAttr<DLLImportAttr>())
1158    GV->setLinkage(llvm::Function::DLLImportLinkage);
1159  else if (D->hasAttr<DLLExportAttr>())
1160    GV->setLinkage(llvm::Function::DLLExportLinkage);
1161  else if (D->hasAttr<WeakAttr>()) {
1162    if (GV->isConstant())
1163      GV->setLinkage(llvm::GlobalVariable::WeakODRLinkage);
1164    else
1165      GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);
1166  } else if (Linkage == GVA_TemplateInstantiation ||
1167             Linkage == GVA_ExplicitTemplateInstantiation)
1168    // FIXME: It seems like we can provide more specific linkage here
1169    // (LinkOnceODR, WeakODR).
1170    GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);
1171  else if (!getLangOptions().CPlusPlus && !CodeGenOpts.NoCommon &&
1172           !D->hasExternalStorage() && !D->getInit() &&
1173           !D->getAttr<SectionAttr>()) {
1174    GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
1175    // common vars aren't constant even if declared const.
1176    GV->setConstant(false);
1177  } else
1178    GV->setLinkage(llvm::GlobalVariable::ExternalLinkage);
1179
1180  SetCommonAttributes(D, GV);
1181
1182  // Emit global variable debug information.
1183  if (CGDebugInfo *DI = getDebugInfo()) {
1184    DI->setLocation(D->getLocation());
1185    DI->EmitGlobalVariable(GV, D);
1186  }
1187}
1188
1189/// ReplaceUsesOfNonProtoTypeWithRealFunction - This function is called when we
1190/// implement a function with no prototype, e.g. "int foo() {}".  If there are
1191/// existing call uses of the old function in the module, this adjusts them to
1192/// call the new function directly.
1193///
1194/// This is not just a cleanup: the always_inline pass requires direct calls to
1195/// functions to be able to inline them.  If there is a bitcast in the way, it
1196/// won't inline them.  Instcombine normally deletes these calls, but it isn't
1197/// run at -O0.
1198static void ReplaceUsesOfNonProtoTypeWithRealFunction(llvm::GlobalValue *Old,
1199                                                      llvm::Function *NewFn) {
1200  // If we're redefining a global as a function, don't transform it.
1201  llvm::Function *OldFn = dyn_cast<llvm::Function>(Old);
1202  if (OldFn == 0) return;
1203
1204  const llvm::Type *NewRetTy = NewFn->getReturnType();
1205  llvm::SmallVector<llvm::Value*, 4> ArgList;
1206
1207  for (llvm::Value::use_iterator UI = OldFn->use_begin(), E = OldFn->use_end();
1208       UI != E; ) {
1209    // TODO: Do invokes ever occur in C code?  If so, we should handle them too.
1210    llvm::Value::use_iterator I = UI++; // Increment before the CI is erased.
1211    llvm::CallInst *CI = dyn_cast<llvm::CallInst>(*I);
1212    llvm::CallSite CS(CI);
1213    if (!CI || !CS.isCallee(I)) continue;
1214
1215    // If the return types don't match exactly, and if the call isn't dead, then
1216    // we can't transform this call.
1217    if (CI->getType() != NewRetTy && !CI->use_empty())
1218      continue;
1219
1220    // If the function was passed too few arguments, don't transform.  If extra
1221    // arguments were passed, we silently drop them.  If any of the types
1222    // mismatch, we don't transform.
1223    unsigned ArgNo = 0;
1224    bool DontTransform = false;
1225    for (llvm::Function::arg_iterator AI = NewFn->arg_begin(),
1226         E = NewFn->arg_end(); AI != E; ++AI, ++ArgNo) {
1227      if (CS.arg_size() == ArgNo ||
1228          CS.getArgument(ArgNo)->getType() != AI->getType()) {
1229        DontTransform = true;
1230        break;
1231      }
1232    }
1233    if (DontTransform)
1234      continue;
1235
1236    // Okay, we can transform this.  Create the new call instruction and copy
1237    // over the required information.
1238    ArgList.append(CS.arg_begin(), CS.arg_begin() + ArgNo);
1239    llvm::CallInst *NewCall = llvm::CallInst::Create(NewFn, ArgList.begin(),
1240                                                     ArgList.end(), "", CI);
1241    ArgList.clear();
1242    if (!NewCall->getType()->isVoidTy())
1243      NewCall->takeName(CI);
1244    NewCall->setAttributes(CI->getAttributes());
1245    NewCall->setCallingConv(CI->getCallingConv());
1246
1247    // Finally, remove the old call, replacing any uses with the new one.
1248    if (!CI->use_empty())
1249      CI->replaceAllUsesWith(NewCall);
1250
1251    // Copy debug location attached to CI.
1252    if (!CI->getDebugLoc().isUnknown())
1253      NewCall->setDebugLoc(CI->getDebugLoc());
1254    CI->eraseFromParent();
1255  }
1256}
1257
1258
1259void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD) {
1260  const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
1261  const llvm::FunctionType *Ty = getTypes().GetFunctionType(GD);
1262  getMangleContext().mangleInitDiscriminator();
1263  // Get or create the prototype for the function.
1264  llvm::Constant *Entry = GetAddrOfFunction(GD, Ty);
1265
1266  // Strip off a bitcast if we got one back.
1267  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
1268    assert(CE->getOpcode() == llvm::Instruction::BitCast);
1269    Entry = CE->getOperand(0);
1270  }
1271
1272
1273  if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != Ty) {
1274    llvm::GlobalValue *OldFn = cast<llvm::GlobalValue>(Entry);
1275
1276    // If the types mismatch then we have to rewrite the definition.
1277    assert(OldFn->isDeclaration() &&
1278           "Shouldn't replace non-declaration");
1279
1280    // F is the Function* for the one with the wrong type, we must make a new
1281    // Function* and update everything that used F (a declaration) with the new
1282    // Function* (which will be a definition).
1283    //
1284    // This happens if there is a prototype for a function
1285    // (e.g. "int f()") and then a definition of a different type
1286    // (e.g. "int f(int x)").  Move the old function aside so that it
1287    // doesn't interfere with GetAddrOfFunction.
1288    OldFn->setName(llvm::StringRef());
1289    llvm::Function *NewFn = cast<llvm::Function>(GetAddrOfFunction(GD, Ty));
1290
1291    // If this is an implementation of a function without a prototype, try to
1292    // replace any existing uses of the function (which may be calls) with uses
1293    // of the new function
1294    if (D->getType()->isFunctionNoProtoType()) {
1295      ReplaceUsesOfNonProtoTypeWithRealFunction(OldFn, NewFn);
1296      OldFn->removeDeadConstantUsers();
1297    }
1298
1299    // Replace uses of F with the Function we will endow with a body.
1300    if (!Entry->use_empty()) {
1301      llvm::Constant *NewPtrForOldDecl =
1302        llvm::ConstantExpr::getBitCast(NewFn, Entry->getType());
1303      Entry->replaceAllUsesWith(NewPtrForOldDecl);
1304    }
1305
1306    // Ok, delete the old function now, which is dead.
1307    OldFn->eraseFromParent();
1308
1309    Entry = NewFn;
1310  }
1311
1312  llvm::Function *Fn = cast<llvm::Function>(Entry);
1313
1314  CodeGenFunction(*this).GenerateCode(D, Fn);
1315
1316  SetFunctionDefinitionAttributes(D, Fn);
1317  SetLLVMFunctionAttributesForDefinition(D, Fn);
1318
1319  if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>())
1320    AddGlobalCtor(Fn, CA->getPriority());
1321  if (const DestructorAttr *DA = D->getAttr<DestructorAttr>())
1322    AddGlobalDtor(Fn, DA->getPriority());
1323}
1324
1325void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
1326  const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
1327  const AliasAttr *AA = D->getAttr<AliasAttr>();
1328  assert(AA && "Not an alias?");
1329
1330  MangleBuffer MangledName;
1331  getMangledName(MangledName, GD);
1332
1333  // If there is a definition in the module, then it wins over the alias.
1334  // This is dubious, but allow it to be safe.  Just ignore the alias.
1335  llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
1336  if (Entry && !Entry->isDeclaration())
1337    return;
1338
1339  const llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
1340
1341  // Create a reference to the named value.  This ensures that it is emitted
1342  // if a deferred decl.
1343  llvm::Constant *Aliasee;
1344  if (isa<llvm::FunctionType>(DeclTy))
1345    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl());
1346  else
1347    Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
1348                                    llvm::PointerType::getUnqual(DeclTy), 0);
1349
1350  // Create the new alias itself, but don't set a name yet.
1351  llvm::GlobalValue *GA =
1352    new llvm::GlobalAlias(Aliasee->getType(),
1353                          llvm::Function::ExternalLinkage,
1354                          "", Aliasee, &getModule());
1355
1356  if (Entry) {
1357    assert(Entry->isDeclaration());
1358
1359    // If there is a declaration in the module, then we had an extern followed
1360    // by the alias, as in:
1361    //   extern int test6();
1362    //   ...
1363    //   int test6() __attribute__((alias("test7")));
1364    //
1365    // Remove it and replace uses of it with the alias.
1366    GA->takeName(Entry);
1367
1368    Entry->replaceAllUsesWith(llvm::ConstantExpr::getBitCast(GA,
1369                                                          Entry->getType()));
1370    Entry->eraseFromParent();
1371  } else {
1372    GA->setName(MangledName.getString());
1373  }
1374
1375  // Set attributes which are particular to an alias; this is a
1376  // specialization of the attributes which may be set on a global
1377  // variable/function.
1378  if (D->hasAttr<DLLExportAttr>()) {
1379    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
1380      // The dllexport attribute is ignored for undefined symbols.
1381      if (FD->getBody())
1382        GA->setLinkage(llvm::Function::DLLExportLinkage);
1383    } else {
1384      GA->setLinkage(llvm::Function::DLLExportLinkage);
1385    }
1386  } else if (D->hasAttr<WeakAttr>() ||
1387             D->hasAttr<WeakRefAttr>() ||
1388             D->hasAttr<WeakImportAttr>()) {
1389    GA->setLinkage(llvm::Function::WeakAnyLinkage);
1390  }
1391
1392  SetCommonAttributes(D, GA);
1393}
1394
1395/// getBuiltinLibFunction - Given a builtin id for a function like
1396/// "__builtin_fabsf", return a Function* for "fabsf".
1397llvm::Value *CodeGenModule::getBuiltinLibFunction(const FunctionDecl *FD,
1398                                                  unsigned BuiltinID) {
1399  assert((Context.BuiltinInfo.isLibFunction(BuiltinID) ||
1400          Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) &&
1401         "isn't a lib fn");
1402
1403  // Get the name, skip over the __builtin_ prefix (if necessary).
1404  const char *Name = Context.BuiltinInfo.GetName(BuiltinID);
1405  if (Context.BuiltinInfo.isLibFunction(BuiltinID))
1406    Name += 10;
1407
1408  const llvm::FunctionType *Ty =
1409    cast<llvm::FunctionType>(getTypes().ConvertType(FD->getType()));
1410
1411  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl(FD));
1412}
1413
1414llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
1415                                            unsigned NumTys) {
1416  return llvm::Intrinsic::getDeclaration(&getModule(),
1417                                         (llvm::Intrinsic::ID)IID, Tys, NumTys);
1418}
1419
1420
1421llvm::Function *CodeGenModule::getMemCpyFn(const llvm::Type *DestType,
1422                                           const llvm::Type *SrcType,
1423                                           const llvm::Type *SizeType) {
1424  const llvm::Type *ArgTypes[3] = {DestType, SrcType, SizeType };
1425  return getIntrinsic(llvm::Intrinsic::memcpy, ArgTypes, 3);
1426}
1427
1428llvm::Function *CodeGenModule::getMemMoveFn(const llvm::Type *DestType,
1429                                            const llvm::Type *SrcType,
1430                                            const llvm::Type *SizeType) {
1431  const llvm::Type *ArgTypes[3] = {DestType, SrcType, SizeType };
1432  return getIntrinsic(llvm::Intrinsic::memmove, ArgTypes, 3);
1433}
1434
1435llvm::Function *CodeGenModule::getMemSetFn(const llvm::Type *DestType,
1436                                           const llvm::Type *SizeType) {
1437  const llvm::Type *ArgTypes[2] = { DestType, SizeType };
1438  return getIntrinsic(llvm::Intrinsic::memset, ArgTypes, 2);
1439}
1440
1441static llvm::StringMapEntry<llvm::Constant*> &
1442GetConstantCFStringEntry(llvm::StringMap<llvm::Constant*> &Map,
1443                         const StringLiteral *Literal,
1444                         bool TargetIsLSB,
1445                         bool &IsUTF16,
1446                         unsigned &StringLength) {
1447  unsigned NumBytes = Literal->getByteLength();
1448
1449  // Check for simple case.
1450  if (!Literal->containsNonAsciiOrNull()) {
1451    StringLength = NumBytes;
1452    return Map.GetOrCreateValue(llvm::StringRef(Literal->getStrData(),
1453                                                StringLength));
1454  }
1455
1456  // Otherwise, convert the UTF8 literals into a byte string.
1457  llvm::SmallVector<UTF16, 128> ToBuf(NumBytes);
1458  const UTF8 *FromPtr = (UTF8 *)Literal->getStrData();
1459  UTF16 *ToPtr = &ToBuf[0];
1460
1461  ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1462                                               &ToPtr, ToPtr + NumBytes,
1463                                               strictConversion);
1464
1465  // Check for conversion failure.
1466  if (Result != conversionOK) {
1467    // FIXME: Have Sema::CheckObjCString() validate the UTF-8 string and remove
1468    // this duplicate code.
1469    assert(Result == sourceIllegal && "UTF-8 to UTF-16 conversion failed");
1470    StringLength = NumBytes;
1471    return Map.GetOrCreateValue(llvm::StringRef(Literal->getStrData(),
1472                                                StringLength));
1473  }
1474
1475  // ConvertUTF8toUTF16 returns the length in ToPtr.
1476  StringLength = ToPtr - &ToBuf[0];
1477
1478  // Render the UTF-16 string into a byte array and convert to the target byte
1479  // order.
1480  //
1481  // FIXME: This isn't something we should need to do here.
1482  llvm::SmallString<128> AsBytes;
1483  AsBytes.reserve(StringLength * 2);
1484  for (unsigned i = 0; i != StringLength; ++i) {
1485    unsigned short Val = ToBuf[i];
1486    if (TargetIsLSB) {
1487      AsBytes.push_back(Val & 0xFF);
1488      AsBytes.push_back(Val >> 8);
1489    } else {
1490      AsBytes.push_back(Val >> 8);
1491      AsBytes.push_back(Val & 0xFF);
1492    }
1493  }
1494  // Append one extra null character, the second is automatically added by our
1495  // caller.
1496  AsBytes.push_back(0);
1497
1498  IsUTF16 = true;
1499  return Map.GetOrCreateValue(llvm::StringRef(AsBytes.data(), AsBytes.size()));
1500}
1501
1502llvm::Constant *
1503CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
1504  unsigned StringLength = 0;
1505  bool isUTF16 = false;
1506  llvm::StringMapEntry<llvm::Constant*> &Entry =
1507    GetConstantCFStringEntry(CFConstantStringMap, Literal,
1508                             getTargetData().isLittleEndian(),
1509                             isUTF16, StringLength);
1510
1511  if (llvm::Constant *C = Entry.getValue())
1512    return C;
1513
1514  llvm::Constant *Zero =
1515      llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext));
1516  llvm::Constant *Zeros[] = { Zero, Zero };
1517
1518  // If we don't already have it, get __CFConstantStringClassReference.
1519  if (!CFConstantStringClassRef) {
1520    const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
1521    Ty = llvm::ArrayType::get(Ty, 0);
1522    llvm::Constant *GV = CreateRuntimeVariable(Ty,
1523                                           "__CFConstantStringClassReference");
1524    // Decay array -> ptr
1525    CFConstantStringClassRef =
1526      llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
1527  }
1528
1529  QualType CFTy = getContext().getCFConstantStringType();
1530
1531  const llvm::StructType *STy =
1532    cast<llvm::StructType>(getTypes().ConvertType(CFTy));
1533
1534  std::vector<llvm::Constant*> Fields(4);
1535
1536  // Class pointer.
1537  Fields[0] = CFConstantStringClassRef;
1538
1539  // Flags.
1540  const llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
1541  Fields[1] = isUTF16 ? llvm::ConstantInt::get(Ty, 0x07d0) :
1542    llvm::ConstantInt::get(Ty, 0x07C8);
1543
1544  // String pointer.
1545  llvm::Constant *C = llvm::ConstantArray::get(VMContext, Entry.getKey().str());
1546
1547  llvm::GlobalValue::LinkageTypes Linkage;
1548  bool isConstant;
1549  if (isUTF16) {
1550    // FIXME: why do utf strings get "_" labels instead of "L" labels?
1551    Linkage = llvm::GlobalValue::InternalLinkage;
1552    // Note: -fwritable-strings doesn't make unicode CFStrings writable, but
1553    // does make plain ascii ones writable.
1554    isConstant = true;
1555  } else {
1556    Linkage = llvm::GlobalValue::PrivateLinkage;
1557    isConstant = !Features.WritableStrings;
1558  }
1559
1560  llvm::GlobalVariable *GV =
1561    new llvm::GlobalVariable(getModule(), C->getType(), isConstant, Linkage, C,
1562                             ".str");
1563  if (isUTF16) {
1564    CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy);
1565    GV->setAlignment(Align.getQuantity());
1566  }
1567  Fields[2] = llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
1568
1569  // String length.
1570  Ty = getTypes().ConvertType(getContext().LongTy);
1571  Fields[3] = llvm::ConstantInt::get(Ty, StringLength);
1572
1573  // The struct.
1574  C = llvm::ConstantStruct::get(STy, Fields);
1575  GV = new llvm::GlobalVariable(getModule(), C->getType(), true,
1576                                llvm::GlobalVariable::PrivateLinkage, C,
1577                                "_unnamed_cfstring_");
1578  if (const char *Sect = getContext().Target.getCFStringSection())
1579    GV->setSection(Sect);
1580  Entry.setValue(GV);
1581
1582  return GV;
1583}
1584
1585/// GetStringForStringLiteral - Return the appropriate bytes for a
1586/// string literal, properly padded to match the literal type.
1587std::string CodeGenModule::GetStringForStringLiteral(const StringLiteral *E) {
1588  const char *StrData = E->getStrData();
1589  unsigned Len = E->getByteLength();
1590
1591  const ConstantArrayType *CAT =
1592    getContext().getAsConstantArrayType(E->getType());
1593  assert(CAT && "String isn't pointer or array!");
1594
1595  // Resize the string to the right size.
1596  std::string Str(StrData, StrData+Len);
1597  uint64_t RealLen = CAT->getSize().getZExtValue();
1598
1599  if (E->isWide())
1600    RealLen *= getContext().Target.getWCharWidth()/8;
1601
1602  Str.resize(RealLen, '\0');
1603
1604  return Str;
1605}
1606
1607/// GetAddrOfConstantStringFromLiteral - Return a pointer to a
1608/// constant array for the given string literal.
1609llvm::Constant *
1610CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
1611  // FIXME: This can be more efficient.
1612  // FIXME: We shouldn't need to bitcast the constant in the wide string case.
1613  llvm::Constant *C = GetAddrOfConstantString(GetStringForStringLiteral(S));
1614  if (S->isWide()) {
1615    llvm::Type *DestTy =
1616        llvm::PointerType::getUnqual(getTypes().ConvertType(S->getType()));
1617    C = llvm::ConstantExpr::getBitCast(C, DestTy);
1618  }
1619  return C;
1620}
1621
1622/// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
1623/// array for the given ObjCEncodeExpr node.
1624llvm::Constant *
1625CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
1626  std::string Str;
1627  getContext().getObjCEncodingForType(E->getEncodedType(), Str);
1628
1629  return GetAddrOfConstantCString(Str);
1630}
1631
1632
1633/// GenerateWritableString -- Creates storage for a string literal.
1634static llvm::Constant *GenerateStringLiteral(const std::string &str,
1635                                             bool constant,
1636                                             CodeGenModule &CGM,
1637                                             const char *GlobalName) {
1638  // Create Constant for this string literal. Don't add a '\0'.
1639  llvm::Constant *C =
1640      llvm::ConstantArray::get(CGM.getLLVMContext(), str, false);
1641
1642  // Create a global variable for this string
1643  return new llvm::GlobalVariable(CGM.getModule(), C->getType(), constant,
1644                                  llvm::GlobalValue::PrivateLinkage,
1645                                  C, GlobalName);
1646}
1647
1648/// GetAddrOfConstantString - Returns a pointer to a character array
1649/// containing the literal. This contents are exactly that of the
1650/// given string, i.e. it will not be null terminated automatically;
1651/// see GetAddrOfConstantCString. Note that whether the result is
1652/// actually a pointer to an LLVM constant depends on
1653/// Feature.WriteableStrings.
1654///
1655/// The result has pointer to array type.
1656llvm::Constant *CodeGenModule::GetAddrOfConstantString(const std::string &str,
1657                                                       const char *GlobalName) {
1658  bool IsConstant = !Features.WritableStrings;
1659
1660  // Get the default prefix if a name wasn't specified.
1661  if (!GlobalName)
1662    GlobalName = ".str";
1663
1664  // Don't share any string literals if strings aren't constant.
1665  if (!IsConstant)
1666    return GenerateStringLiteral(str, false, *this, GlobalName);
1667
1668  llvm::StringMapEntry<llvm::Constant *> &Entry =
1669    ConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
1670
1671  if (Entry.getValue())
1672    return Entry.getValue();
1673
1674  // Create a global variable for this.
1675  llvm::Constant *C = GenerateStringLiteral(str, true, *this, GlobalName);
1676  Entry.setValue(C);
1677  return C;
1678}
1679
1680/// GetAddrOfConstantCString - Returns a pointer to a character
1681/// array containing the literal and a terminating '\-'
1682/// character. The result has pointer to array type.
1683llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &str,
1684                                                        const char *GlobalName){
1685  return GetAddrOfConstantString(str + '\0', GlobalName);
1686}
1687
1688/// EmitObjCPropertyImplementations - Emit information for synthesized
1689/// properties for an implementation.
1690void CodeGenModule::EmitObjCPropertyImplementations(const
1691                                                    ObjCImplementationDecl *D) {
1692  for (ObjCImplementationDecl::propimpl_iterator
1693         i = D->propimpl_begin(), e = D->propimpl_end(); i != e; ++i) {
1694    ObjCPropertyImplDecl *PID = *i;
1695
1696    // Dynamic is just for type-checking.
1697    if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
1698      ObjCPropertyDecl *PD = PID->getPropertyDecl();
1699
1700      // Determine which methods need to be implemented, some may have
1701      // been overridden. Note that ::isSynthesized is not the method
1702      // we want, that just indicates if the decl came from a
1703      // property. What we want to know is if the method is defined in
1704      // this implementation.
1705      if (!D->getInstanceMethod(PD->getGetterName()))
1706        CodeGenFunction(*this).GenerateObjCGetter(
1707                                 const_cast<ObjCImplementationDecl *>(D), PID);
1708      if (!PD->isReadOnly() &&
1709          !D->getInstanceMethod(PD->getSetterName()))
1710        CodeGenFunction(*this).GenerateObjCSetter(
1711                                 const_cast<ObjCImplementationDecl *>(D), PID);
1712    }
1713  }
1714}
1715
1716/// EmitNamespace - Emit all declarations in a namespace.
1717void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
1718  for (RecordDecl::decl_iterator I = ND->decls_begin(), E = ND->decls_end();
1719       I != E; ++I)
1720    EmitTopLevelDecl(*I);
1721}
1722
1723// EmitLinkageSpec - Emit all declarations in a linkage spec.
1724void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
1725  if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
1726      LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
1727    ErrorUnsupported(LSD, "linkage spec");
1728    return;
1729  }
1730
1731  for (RecordDecl::decl_iterator I = LSD->decls_begin(), E = LSD->decls_end();
1732       I != E; ++I)
1733    EmitTopLevelDecl(*I);
1734}
1735
1736/// EmitTopLevelDecl - Emit code for a single top level declaration.
1737void CodeGenModule::EmitTopLevelDecl(Decl *D) {
1738  // If an error has occurred, stop code generation, but continue
1739  // parsing and semantic analysis (to ensure all warnings and errors
1740  // are emitted).
1741  if (Diags.hasErrorOccurred())
1742    return;
1743
1744  // Ignore dependent declarations.
1745  if (D->getDeclContext() && D->getDeclContext()->isDependentContext())
1746    return;
1747
1748  switch (D->getKind()) {
1749  case Decl::CXXConversion:
1750  case Decl::CXXMethod:
1751  case Decl::Function:
1752    // Skip function templates
1753    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate())
1754      return;
1755
1756    EmitGlobal(cast<FunctionDecl>(D));
1757    break;
1758
1759  case Decl::Var:
1760    EmitGlobal(cast<VarDecl>(D));
1761    break;
1762
1763  // C++ Decls
1764  case Decl::Namespace:
1765    EmitNamespace(cast<NamespaceDecl>(D));
1766    break;
1767    // No code generation needed.
1768  case Decl::UsingShadow:
1769  case Decl::Using:
1770  case Decl::UsingDirective:
1771  case Decl::ClassTemplate:
1772  case Decl::FunctionTemplate:
1773  case Decl::NamespaceAlias:
1774    break;
1775  case Decl::CXXConstructor:
1776    // Skip function templates
1777    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate())
1778      return;
1779
1780    EmitCXXConstructors(cast<CXXConstructorDecl>(D));
1781    break;
1782  case Decl::CXXDestructor:
1783    EmitCXXDestructors(cast<CXXDestructorDecl>(D));
1784    break;
1785
1786  case Decl::StaticAssert:
1787    // Nothing to do.
1788    break;
1789
1790  // Objective-C Decls
1791
1792  // Forward declarations, no (immediate) code generation.
1793  case Decl::ObjCClass:
1794  case Decl::ObjCForwardProtocol:
1795  case Decl::ObjCCategory:
1796  case Decl::ObjCInterface:
1797    break;
1798
1799  case Decl::ObjCProtocol:
1800    Runtime->GenerateProtocol(cast<ObjCProtocolDecl>(D));
1801    break;
1802
1803  case Decl::ObjCCategoryImpl:
1804    // Categories have properties but don't support synthesize so we
1805    // can ignore them here.
1806    Runtime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
1807    break;
1808
1809  case Decl::ObjCImplementation: {
1810    ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
1811    EmitObjCPropertyImplementations(OMD);
1812    Runtime->GenerateClass(OMD);
1813    break;
1814  }
1815  case Decl::ObjCMethod: {
1816    ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
1817    // If this is not a prototype, emit the body.
1818    if (OMD->getBody())
1819      CodeGenFunction(*this).GenerateObjCMethod(OMD);
1820    break;
1821  }
1822  case Decl::ObjCCompatibleAlias:
1823    // compatibility-alias is a directive and has no code gen.
1824    break;
1825
1826  case Decl::LinkageSpec:
1827    EmitLinkageSpec(cast<LinkageSpecDecl>(D));
1828    break;
1829
1830  case Decl::FileScopeAsm: {
1831    FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
1832    llvm::StringRef AsmString = AD->getAsmString()->getString();
1833
1834    const std::string &S = getModule().getModuleInlineAsm();
1835    if (S.empty())
1836      getModule().setModuleInlineAsm(AsmString);
1837    else
1838      getModule().setModuleInlineAsm(S + '\n' + AsmString.str());
1839    break;
1840  }
1841
1842  default:
1843    // Make sure we handled everything we should, every other kind is a
1844    // non-top-level decl.  FIXME: Would be nice to have an isTopLevelDeclKind
1845    // function. Need to recode Decl::Kind to do that easily.
1846    assert(isa<TypeDecl>(D) && "Unsupported decl kind");
1847  }
1848}
1849