CodeGenModule.cpp revision af4403545a50a60d208e6fcae057308d576a92e0 
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/ErrorHandling.h"
39using namespace clang;
40using namespace CodeGen;
41
42
43CodeGenModule::CodeGenModule(ASTContext &C, const CodeGenOptions &CGO,
44                             llvm::Module &M, const llvm::TargetData &TD,
45                             Diagnostic &diags)
46  : BlockModule(C, M, TD, Types, *this), Context(C),
47    Features(C.getLangOptions()), CodeGenOpts(CGO), TheModule(M),
48    TheTargetData(TD), TheTargetCodeGenInfo(0), Diags(diags),
49    Types(C, M, TD, getTargetCodeGenInfo().getABIInfo()),
50    MangleCtx(C), VTables(*this), Runtime(0),
51    MemCpyFn(0), MemMoveFn(0), MemSetFn(0), CFConstantStringClassRef(0),
52    VMContext(M.getContext()) {
53
54  if (!Features.ObjC1)
55    Runtime = 0;
56  else if (!Features.NeXTRuntime)
57    Runtime = CreateGNUObjCRuntime(*this);
58  else if (Features.ObjCNonFragileABI)
59    Runtime = CreateMacNonFragileABIObjCRuntime(*this);
60  else
61    Runtime = CreateMacObjCRuntime(*this);
62
63  // If debug info generation is enabled, create the CGDebugInfo object.
64  DebugInfo = CodeGenOpts.DebugInfo ? new CGDebugInfo(*this) : 0;
65}
66
67CodeGenModule::~CodeGenModule() {
68  delete Runtime;
69  delete DebugInfo;
70}
71
72void CodeGenModule::createObjCRuntime() {
73  if (!Features.NeXTRuntime)
74    Runtime = CreateGNUObjCRuntime(*this);
75  else if (Features.ObjCNonFragileABI)
76    Runtime = CreateMacNonFragileABIObjCRuntime(*this);
77  else
78    Runtime = CreateMacObjCRuntime(*this);
79}
80
81void CodeGenModule::Release() {
82  EmitDeferred();
83  EmitCXXGlobalInitFunc();
84  EmitCXXGlobalDtorFunc();
85  if (Runtime)
86    if (llvm::Function *ObjCInitFunction = Runtime->ModuleInitFunction())
87      AddGlobalCtor(ObjCInitFunction);
88  EmitCtorList(GlobalCtors, "llvm.global_ctors");
89  EmitCtorList(GlobalDtors, "llvm.global_dtors");
90  EmitAnnotations();
91  EmitLLVMUsed();
92}
93
94bool CodeGenModule::isTargetDarwin() const {
95  return getContext().Target.getTriple().getOS() == llvm::Triple::Darwin;
96}
97
98/// ErrorUnsupported - Print out an error that codegen doesn't support the
99/// specified stmt yet.
100void CodeGenModule::ErrorUnsupported(const Stmt *S, const char *Type,
101                                     bool OmitOnError) {
102  if (OmitOnError && getDiags().hasErrorOccurred())
103    return;
104  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
105                                               "cannot compile this %0 yet");
106  std::string Msg = Type;
107  getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID)
108    << Msg << S->getSourceRange();
109}
110
111/// ErrorUnsupported - Print out an error that codegen doesn't support the
112/// specified decl yet.
113void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type,
114                                     bool OmitOnError) {
115  if (OmitOnError && getDiags().hasErrorOccurred())
116    return;
117  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
118                                               "cannot compile this %0 yet");
119  std::string Msg = Type;
120  getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID) << Msg;
121}
122
123LangOptions::VisibilityMode
124CodeGenModule::getDeclVisibilityMode(const Decl *D) const {
125  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
126    if (VD->getStorageClass() == VarDecl::PrivateExtern)
127      return LangOptions::Hidden;
128
129  if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>()) {
130    switch (attr->getVisibility()) {
131    default: assert(0 && "Unknown visibility!");
132    case VisibilityAttr::DefaultVisibility:
133      return LangOptions::Default;
134    case VisibilityAttr::HiddenVisibility:
135      return LangOptions::Hidden;
136    case VisibilityAttr::ProtectedVisibility:
137      return LangOptions::Protected;
138    }
139  }
140
141  // This decl should have the same visibility as its parent.
142  if (const DeclContext *DC = D->getDeclContext())
143    return getDeclVisibilityMode(cast<Decl>(DC));
144
145  return getLangOptions().getVisibilityMode();
146}
147
148void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
149                                        const Decl *D) const {
150  // Internal definitions always have default visibility.
151  if (GV->hasLocalLinkage()) {
152    GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
153    return;
154  }
155
156  switch (getDeclVisibilityMode(D)) {
157  default: assert(0 && "Unknown visibility!");
158  case LangOptions::Default:
159    return GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
160  case LangOptions::Hidden:
161    return GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
162  case LangOptions::Protected:
163    return GV->setVisibility(llvm::GlobalValue::ProtectedVisibility);
164  }
165}
166
167void CodeGenModule::getMangledName(MangleBuffer &Buffer, GlobalDecl GD) {
168  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
169
170  if (const CXXConstructorDecl *D = dyn_cast<CXXConstructorDecl>(ND))
171    return getMangledCXXCtorName(Buffer, D, GD.getCtorType());
172  if (const CXXDestructorDecl *D = dyn_cast<CXXDestructorDecl>(ND))
173    return getMangledCXXDtorName(Buffer, D, GD.getDtorType());
174
175  return getMangledName(Buffer, ND);
176}
177
178/// \brief Retrieves the mangled name for the given declaration.
179///
180/// If the given declaration requires a mangled name, returns an
181/// const char* containing the mangled name.  Otherwise, returns
182/// the unmangled name.
183///
184void CodeGenModule::getMangledName(MangleBuffer &Buffer,
185                                   const NamedDecl *ND) {
186  if (!getMangleContext().shouldMangleDeclName(ND)) {
187    assert(ND->getIdentifier() && "Attempt to mangle unnamed decl.");
188    Buffer.setString(ND->getNameAsCString());
189    return;
190  }
191
192  getMangleContext().mangleName(ND, Buffer.getBuffer());
193}
194
195llvm::GlobalValue *CodeGenModule::GetGlobalValue(llvm::StringRef Name) {
196  return getModule().getNamedValue(Name);
197}
198
199/// AddGlobalCtor - Add a function to the list that will be called before
200/// main() runs.
201void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor, int Priority) {
202  // FIXME: Type coercion of void()* types.
203  GlobalCtors.push_back(std::make_pair(Ctor, Priority));
204}
205
206/// AddGlobalDtor - Add a function to the list that will be called
207/// when the module is unloaded.
208void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
209  // FIXME: Type coercion of void()* types.
210  GlobalDtors.push_back(std::make_pair(Dtor, Priority));
211}
212
213void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
214  // Ctor function type is void()*.
215  llvm::FunctionType* CtorFTy =
216    llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
217                            std::vector<const llvm::Type*>(),
218                            false);
219  llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
220
221  // Get the type of a ctor entry, { i32, void ()* }.
222  llvm::StructType* CtorStructTy =
223    llvm::StructType::get(VMContext, llvm::Type::getInt32Ty(VMContext),
224                          llvm::PointerType::getUnqual(CtorFTy), NULL);
225
226  // Construct the constructor and destructor arrays.
227  std::vector<llvm::Constant*> Ctors;
228  for (CtorList::const_iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
229    std::vector<llvm::Constant*> S;
230    S.push_back(llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
231                I->second, false));
232    S.push_back(llvm::ConstantExpr::getBitCast(I->first, CtorPFTy));
233    Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
234  }
235
236  if (!Ctors.empty()) {
237    llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
238    new llvm::GlobalVariable(TheModule, AT, false,
239                             llvm::GlobalValue::AppendingLinkage,
240                             llvm::ConstantArray::get(AT, Ctors),
241                             GlobalName);
242  }
243}
244
245void CodeGenModule::EmitAnnotations() {
246  if (Annotations.empty())
247    return;
248
249  // Create a new global variable for the ConstantStruct in the Module.
250  llvm::Constant *Array =
251  llvm::ConstantArray::get(llvm::ArrayType::get(Annotations[0]->getType(),
252                                                Annotations.size()),
253                           Annotations);
254  llvm::GlobalValue *gv =
255  new llvm::GlobalVariable(TheModule, Array->getType(), false,
256                           llvm::GlobalValue::AppendingLinkage, Array,
257                           "llvm.global.annotations");
258  gv->setSection("llvm.metadata");
259}
260
261static CodeGenModule::GVALinkage
262GetLinkageForFunction(ASTContext &Context, const FunctionDecl *FD,
263                      const LangOptions &Features) {
264  CodeGenModule::GVALinkage External = CodeGenModule::GVA_StrongExternal;
265
266  Linkage L = FD->getLinkage();
267  if (L == ExternalLinkage && Context.getLangOptions().CPlusPlus &&
268      FD->getType()->getLinkage() == UniqueExternalLinkage)
269    L = UniqueExternalLinkage;
270
271  switch (L) {
272  case NoLinkage:
273  case InternalLinkage:
274  case UniqueExternalLinkage:
275    return CodeGenModule::GVA_Internal;
276
277  case ExternalLinkage:
278    switch (FD->getTemplateSpecializationKind()) {
279    case TSK_Undeclared:
280    case TSK_ExplicitSpecialization:
281      External = CodeGenModule::GVA_StrongExternal;
282      break;
283
284    case TSK_ExplicitInstantiationDefinition:
285      return CodeGenModule::GVA_ExplicitTemplateInstantiation;
286
287    case TSK_ExplicitInstantiationDeclaration:
288    case TSK_ImplicitInstantiation:
289      External = CodeGenModule::GVA_TemplateInstantiation;
290      break;
291    }
292  }
293
294  if (!FD->isInlined())
295    return External;
296
297  if (!Features.CPlusPlus || FD->hasAttr<GNUInlineAttr>()) {
298    // GNU or C99 inline semantics. Determine whether this symbol should be
299    // externally visible.
300    if (FD->isInlineDefinitionExternallyVisible())
301      return External;
302
303    // C99 inline semantics, where the symbol is not externally visible.
304    return CodeGenModule::GVA_C99Inline;
305  }
306
307  // C++0x [temp.explicit]p9:
308  //   [ Note: The intent is that an inline function that is the subject of
309  //   an explicit instantiation declaration will still be implicitly
310  //   instantiated when used so that the body can be considered for
311  //   inlining, but that no out-of-line copy of the inline function would be
312  //   generated in the translation unit. -- end note ]
313  if (FD->getTemplateSpecializationKind()
314                                       == TSK_ExplicitInstantiationDeclaration)
315    return CodeGenModule::GVA_C99Inline;
316
317  return CodeGenModule::GVA_CXXInline;
318}
319
320llvm::GlobalValue::LinkageTypes
321CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
322  GVALinkage Linkage = GetLinkageForFunction(getContext(), D, Features);
323
324  if (Linkage == GVA_Internal) {
325    return llvm::Function::InternalLinkage;
326  } else if (D->hasAttr<DLLExportAttr>()) {
327    return llvm::Function::DLLExportLinkage;
328  } else if (D->hasAttr<WeakAttr>()) {
329    return llvm::Function::WeakAnyLinkage;
330  } else if (Linkage == GVA_C99Inline) {
331    // In C99 mode, 'inline' functions are guaranteed to have a strong
332    // definition somewhere else, so we can use available_externally linkage.
333    return llvm::Function::AvailableExternallyLinkage;
334  } else if (Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation) {
335    // In C++, the compiler has to emit a definition in every translation unit
336    // that references the function.  We should use linkonce_odr because
337    // a) if all references in this translation unit are optimized away, we
338    // don't need to codegen it.  b) if the function persists, it needs to be
339    // merged with other definitions. c) C++ has the ODR, so we know the
340    // definition is dependable.
341    return llvm::Function::LinkOnceODRLinkage;
342  } else if (Linkage == GVA_ExplicitTemplateInstantiation) {
343    // An explicit instantiation of a template has weak linkage, since
344    // explicit instantiations can occur in multiple translation units
345    // and must all be equivalent. However, we are not allowed to
346    // throw away these explicit instantiations.
347    return llvm::Function::WeakODRLinkage;
348  } else {
349    assert(Linkage == GVA_StrongExternal);
350    // Otherwise, we have strong external linkage.
351    return llvm::Function::ExternalLinkage;
352  }
353}
354
355
356/// SetFunctionDefinitionAttributes - Set attributes for a global.
357///
358/// FIXME: This is currently only done for aliases and functions, but not for
359/// variables (these details are set in EmitGlobalVarDefinition for variables).
360void CodeGenModule::SetFunctionDefinitionAttributes(const FunctionDecl *D,
361                                                    llvm::GlobalValue *GV) {
362  GV->setLinkage(getFunctionLinkage(D));
363  SetCommonAttributes(D, GV);
364}
365
366void CodeGenModule::SetLLVMFunctionAttributes(const Decl *D,
367                                              const CGFunctionInfo &Info,
368                                              llvm::Function *F) {
369  unsigned CallingConv;
370  AttributeListType AttributeList;
371  ConstructAttributeList(Info, D, AttributeList, CallingConv);
372  F->setAttributes(llvm::AttrListPtr::get(AttributeList.begin(),
373                                          AttributeList.size()));
374  F->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
375}
376
377void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
378                                                           llvm::Function *F) {
379  if (!Features.Exceptions && !Features.ObjCNonFragileABI)
380    F->addFnAttr(llvm::Attribute::NoUnwind);
381
382  if (D->hasAttr<AlwaysInlineAttr>())
383    F->addFnAttr(llvm::Attribute::AlwaysInline);
384
385  if (D->hasAttr<NoInlineAttr>())
386    F->addFnAttr(llvm::Attribute::NoInline);
387
388  if (Features.getStackProtectorMode() == LangOptions::SSPOn)
389    F->addFnAttr(llvm::Attribute::StackProtect);
390  else if (Features.getStackProtectorMode() == LangOptions::SSPReq)
391    F->addFnAttr(llvm::Attribute::StackProtectReq);
392
393  if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) {
394    unsigned width = Context.Target.getCharWidth();
395    F->setAlignment(AA->getAlignment() / width);
396    while ((AA = AA->getNext<AlignedAttr>()))
397      F->setAlignment(std::max(F->getAlignment(), AA->getAlignment() / width));
398  }
399  // C++ ABI requires 2-byte alignment for member functions.
400  if (F->getAlignment() < 2 && isa<CXXMethodDecl>(D))
401    F->setAlignment(2);
402}
403
404void CodeGenModule::SetCommonAttributes(const Decl *D,
405                                        llvm::GlobalValue *GV) {
406  setGlobalVisibility(GV, D);
407
408  if (D->hasAttr<UsedAttr>())
409    AddUsedGlobal(GV);
410
411  if (const SectionAttr *SA = D->getAttr<SectionAttr>())
412    GV->setSection(SA->getName());
413
414  getTargetCodeGenInfo().SetTargetAttributes(D, GV, *this);
415}
416
417void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
418                                                  llvm::Function *F,
419                                                  const CGFunctionInfo &FI) {
420  SetLLVMFunctionAttributes(D, FI, F);
421  SetLLVMFunctionAttributesForDefinition(D, F);
422
423  F->setLinkage(llvm::Function::InternalLinkage);
424
425  SetCommonAttributes(D, F);
426}
427
428void CodeGenModule::SetFunctionAttributes(GlobalDecl GD,
429                                          llvm::Function *F,
430                                          bool IsIncompleteFunction) {
431  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
432
433  if (!IsIncompleteFunction)
434    SetLLVMFunctionAttributes(FD, getTypes().getFunctionInfo(GD), F);
435
436  // Only a few attributes are set on declarations; these may later be
437  // overridden by a definition.
438
439  if (FD->hasAttr<DLLImportAttr>()) {
440    F->setLinkage(llvm::Function::DLLImportLinkage);
441  } else if (FD->hasAttr<WeakAttr>() ||
442             FD->hasAttr<WeakImportAttr>()) {
443    // "extern_weak" is overloaded in LLVM; we probably should have
444    // separate linkage types for this.
445    F->setLinkage(llvm::Function::ExternalWeakLinkage);
446  } else {
447    F->setLinkage(llvm::Function::ExternalLinkage);
448  }
449
450  if (const SectionAttr *SA = FD->getAttr<SectionAttr>())
451    F->setSection(SA->getName());
452}
453
454void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
455  assert(!GV->isDeclaration() &&
456         "Only globals with definition can force usage.");
457  LLVMUsed.push_back(GV);
458}
459
460void CodeGenModule::EmitLLVMUsed() {
461  // Don't create llvm.used if there is no need.
462  if (LLVMUsed.empty())
463    return;
464
465  const llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(VMContext);
466
467  // Convert LLVMUsed to what ConstantArray needs.
468  std::vector<llvm::Constant*> UsedArray;
469  UsedArray.resize(LLVMUsed.size());
470  for (unsigned i = 0, e = LLVMUsed.size(); i != e; ++i) {
471    UsedArray[i] =
472     llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*LLVMUsed[i]),
473                                      i8PTy);
474  }
475
476  if (UsedArray.empty())
477    return;
478  llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, UsedArray.size());
479
480  llvm::GlobalVariable *GV =
481    new llvm::GlobalVariable(getModule(), ATy, false,
482                             llvm::GlobalValue::AppendingLinkage,
483                             llvm::ConstantArray::get(ATy, UsedArray),
484                             "llvm.used");
485
486  GV->setSection("llvm.metadata");
487}
488
489void CodeGenModule::EmitDeferred() {
490  // Emit code for any potentially referenced deferred decls.  Since a
491  // previously unused static decl may become used during the generation of code
492  // for a static function, iterate until no  changes are made.
493
494  while (!DeferredDeclsToEmit.empty() || !DeferredVtables.empty()) {
495    if (!DeferredVtables.empty()) {
496      const CXXRecordDecl *RD = DeferredVtables.back();
497      DeferredVtables.pop_back();
498      getVTables().GenerateClassData(getVtableLinkage(RD), RD);
499      continue;
500    }
501
502    GlobalDecl D = DeferredDeclsToEmit.back();
503    DeferredDeclsToEmit.pop_back();
504
505    // Look it up to see if it was defined with a stronger definition (e.g. an
506    // extern inline function with a strong function redefinition).  If so,
507    // just ignore the deferred decl.
508    MangleBuffer Name;
509    getMangledName(Name, D);
510    llvm::GlobalValue *CGRef = GetGlobalValue(Name);
511    assert(CGRef && "Deferred decl wasn't referenced?");
512
513    if (!CGRef->isDeclaration())
514      continue;
515
516    // Otherwise, emit the definition and move on to the next one.
517    EmitGlobalDefinition(D);
518  }
519}
520
521/// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
522/// annotation information for a given GlobalValue.  The annotation struct is
523/// {i8 *, i8 *, i8 *, i32}.  The first field is a constant expression, the
524/// GlobalValue being annotated.  The second field is the constant string
525/// created from the AnnotateAttr's annotation.  The third field is a constant
526/// string containing the name of the translation unit.  The fourth field is
527/// the line number in the file of the annotated value declaration.
528///
529/// FIXME: this does not unique the annotation string constants, as llvm-gcc
530///        appears to.
531///
532llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
533                                                const AnnotateAttr *AA,
534                                                unsigned LineNo) {
535  llvm::Module *M = &getModule();
536
537  // get [N x i8] constants for the annotation string, and the filename string
538  // which are the 2nd and 3rd elements of the global annotation structure.
539  const llvm::Type *SBP = llvm::Type::getInt8PtrTy(VMContext);
540  llvm::Constant *anno = llvm::ConstantArray::get(VMContext,
541                                                  AA->getAnnotation(), true);
542  llvm::Constant *unit = llvm::ConstantArray::get(VMContext,
543                                                  M->getModuleIdentifier(),
544                                                  true);
545
546  // Get the two global values corresponding to the ConstantArrays we just
547  // created to hold the bytes of the strings.
548  llvm::GlobalValue *annoGV =
549    new llvm::GlobalVariable(*M, anno->getType(), false,
550                             llvm::GlobalValue::PrivateLinkage, anno,
551                             GV->getName());
552  // translation unit name string, emitted into the llvm.metadata section.
553  llvm::GlobalValue *unitGV =
554    new llvm::GlobalVariable(*M, unit->getType(), false,
555                             llvm::GlobalValue::PrivateLinkage, unit,
556                             ".str");
557
558  // Create the ConstantStruct for the global annotation.
559  llvm::Constant *Fields[4] = {
560    llvm::ConstantExpr::getBitCast(GV, SBP),
561    llvm::ConstantExpr::getBitCast(annoGV, SBP),
562    llvm::ConstantExpr::getBitCast(unitGV, SBP),
563    llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), LineNo)
564  };
565  return llvm::ConstantStruct::get(VMContext, Fields, 4, false);
566}
567
568bool CodeGenModule::MayDeferGeneration(const ValueDecl *Global) {
569  // Never defer when EmitAllDecls is specified or the decl has
570  // attribute used.
571  if (Features.EmitAllDecls || Global->hasAttr<UsedAttr>())
572    return false;
573
574  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
575    // Constructors and destructors should never be deferred.
576    if (FD->hasAttr<ConstructorAttr>() ||
577        FD->hasAttr<DestructorAttr>())
578      return false;
579
580    // The key function for a class must never be deferred.
581    if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Global)) {
582      const CXXRecordDecl *RD = MD->getParent();
583      if (MD->isOutOfLine() && RD->isDynamicClass()) {
584        const CXXMethodDecl *KeyFunction = getContext().getKeyFunction(RD);
585        if (KeyFunction &&
586            KeyFunction->getCanonicalDecl() == MD->getCanonicalDecl())
587          return false;
588      }
589    }
590
591    GVALinkage Linkage = GetLinkageForFunction(getContext(), FD, Features);
592
593    // static, static inline, always_inline, and extern inline functions can
594    // always be deferred.  Normal inline functions can be deferred in C99/C++.
595    // Implicit template instantiations can also be deferred in C++.
596    if (Linkage == GVA_Internal || Linkage == GVA_C99Inline ||
597        Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation)
598      return true;
599    return false;
600  }
601
602  const VarDecl *VD = cast<VarDecl>(Global);
603  assert(VD->isFileVarDecl() && "Invalid decl");
604
605  // We never want to defer structs that have non-trivial constructors or
606  // destructors.
607
608  // FIXME: Handle references.
609  if (const RecordType *RT = VD->getType()->getAs<RecordType>()) {
610    if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
611      if (!RD->hasTrivialConstructor() || !RD->hasTrivialDestructor())
612        return false;
613    }
614  }
615
616  // Static data may be deferred, but out-of-line static data members
617  // cannot be.
618  Linkage L = VD->getLinkage();
619  if (L == ExternalLinkage && getContext().getLangOptions().CPlusPlus &&
620      VD->getType()->getLinkage() == UniqueExternalLinkage)
621    L = UniqueExternalLinkage;
622
623  switch (L) {
624  case NoLinkage:
625  case InternalLinkage:
626  case UniqueExternalLinkage:
627    // Initializer has side effects?
628    if (VD->getInit() && VD->getInit()->HasSideEffects(Context))
629      return false;
630    return !(VD->isStaticDataMember() && VD->isOutOfLine());
631
632  case ExternalLinkage:
633    break;
634  }
635
636  return false;
637}
638
639llvm::Constant *CodeGenModule::GetWeakRefReference(const ValueDecl *VD) {
640  const AliasAttr *AA = VD->getAttr<AliasAttr>();
641  assert(AA && "No alias?");
642
643  const llvm::Type *DeclTy = getTypes().ConvertTypeForMem(VD->getType());
644
645  // See if there is already something with the target's name in the module.
646  llvm::GlobalValue *Entry = GetGlobalValue(AA->getAliasee());
647
648  llvm::Constant *Aliasee;
649  if (isa<llvm::FunctionType>(DeclTy))
650    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl());
651  else
652    Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
653                                    llvm::PointerType::getUnqual(DeclTy), 0);
654  if (!Entry) {
655    llvm::GlobalValue* F = cast<llvm::GlobalValue>(Aliasee);
656    F->setLinkage(llvm::Function::ExternalWeakLinkage);
657    WeakRefReferences.insert(F);
658  }
659
660  return Aliasee;
661}
662
663void CodeGenModule::EmitGlobal(GlobalDecl GD) {
664  const ValueDecl *Global = cast<ValueDecl>(GD.getDecl());
665
666  // Weak references don't produce any output by themselves.
667  if (Global->hasAttr<WeakRefAttr>())
668    return;
669
670  // If this is an alias definition (which otherwise looks like a declaration)
671  // emit it now.
672  if (Global->hasAttr<AliasAttr>())
673    return EmitAliasDefinition(GD);
674
675  // Ignore declarations, they will be emitted on their first use.
676  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
677    // Forward declarations are emitted lazily on first use.
678    if (!FD->isThisDeclarationADefinition())
679      return;
680  } else {
681    const VarDecl *VD = cast<VarDecl>(Global);
682    assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
683
684    if (VD->isThisDeclarationADefinition() != VarDecl::Definition)
685      return;
686  }
687
688  // Defer code generation when possible if this is a static definition, inline
689  // function etc.  These we only want to emit if they are used.
690  if (MayDeferGeneration(Global)) {
691    // If the value has already been used, add it directly to the
692    // DeferredDeclsToEmit list.
693    MangleBuffer MangledName;
694    getMangledName(MangledName, GD);
695    if (GetGlobalValue(MangledName))
696      DeferredDeclsToEmit.push_back(GD);
697    else {
698      // Otherwise, remember that we saw a deferred decl with this name.  The
699      // first use of the mangled name will cause it to move into
700      // DeferredDeclsToEmit.
701      DeferredDecls[MangledName] = GD;
702    }
703    return;
704  }
705
706  // Otherwise emit the definition.
707  EmitGlobalDefinition(GD);
708}
709
710void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD) {
711  const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
712
713  PrettyStackTraceDecl CrashInfo((ValueDecl *)D, D->getLocation(),
714                                 Context.getSourceManager(),
715                                 "Generating code for declaration");
716
717  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) {
718    getVTables().MaybeEmitVtable(GD);
719    if (MD->isVirtual() && MD->isOutOfLine() &&
720        (!isa<CXXDestructorDecl>(D) || GD.getDtorType() != Dtor_Base)) {
721      if (isa<CXXDestructorDecl>(D)) {
722        GlobalDecl CanonGD(cast<CXXDestructorDecl>(D->getCanonicalDecl()),
723                           GD.getDtorType());
724        BuildThunksForVirtual(CanonGD);
725      } else {
726        BuildThunksForVirtual(MD->getCanonicalDecl());
727      }
728    }
729  }
730
731  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
732    EmitCXXConstructor(CD, GD.getCtorType());
733  else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(D))
734    EmitCXXDestructor(DD, GD.getDtorType());
735  else if (isa<FunctionDecl>(D))
736    EmitGlobalFunctionDefinition(GD);
737  else if (const VarDecl *VD = dyn_cast<VarDecl>(D))
738    EmitGlobalVarDefinition(VD);
739  else {
740    assert(0 && "Invalid argument to EmitGlobalDefinition()");
741  }
742}
743
744/// GetOrCreateLLVMFunction - If the specified mangled name is not in the
745/// module, create and return an llvm Function with the specified type. If there
746/// is something in the module with the specified name, return it potentially
747/// bitcasted to the right type.
748///
749/// If D is non-null, it specifies a decl that correspond to this.  This is used
750/// to set the attributes on the function when it is first created.
751llvm::Constant *
752CodeGenModule::GetOrCreateLLVMFunction(llvm::StringRef MangledName,
753                                       const llvm::Type *Ty,
754                                       GlobalDecl D) {
755  // Lookup the entry, lazily creating it if necessary.
756  llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
757  if (Entry) {
758    if (WeakRefReferences.count(Entry)) {
759      const FunctionDecl *FD = cast_or_null<FunctionDecl>(D.getDecl());
760      if (FD && !FD->hasAttr<WeakAttr>())
761	Entry->setLinkage(llvm::Function::ExternalLinkage);
762
763      WeakRefReferences.erase(Entry);
764    }
765
766    if (Entry->getType()->getElementType() == Ty)
767      return Entry;
768
769    // Make sure the result is of the correct type.
770    const llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
771    return llvm::ConstantExpr::getBitCast(Entry, PTy);
772  }
773
774  // This function doesn't have a complete type (for example, the return
775  // type is an incomplete struct). Use a fake type instead, and make
776  // sure not to try to set attributes.
777  bool IsIncompleteFunction = false;
778  if (!isa<llvm::FunctionType>(Ty)) {
779    Ty = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
780                                 std::vector<const llvm::Type*>(), false);
781    IsIncompleteFunction = true;
782  }
783  llvm::Function *F = llvm::Function::Create(cast<llvm::FunctionType>(Ty),
784                                             llvm::Function::ExternalLinkage,
785                                             MangledName, &getModule());
786  assert(F->getName() == MangledName && "name was uniqued!");
787  if (D.getDecl())
788    SetFunctionAttributes(D, F, IsIncompleteFunction);
789
790  // This is the first use or definition of a mangled name.  If there is a
791  // deferred decl with this name, remember that we need to emit it at the end
792  // of the file.
793  llvm::StringMap<GlobalDecl>::iterator DDI = DeferredDecls.find(MangledName);
794  if (DDI != DeferredDecls.end()) {
795    // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
796    // list, and remove it from DeferredDecls (since we don't need it anymore).
797    DeferredDeclsToEmit.push_back(DDI->second);
798    DeferredDecls.erase(DDI);
799  } else if (const FunctionDecl *FD = cast_or_null<FunctionDecl>(D.getDecl())) {
800    // If this the first reference to a C++ inline function in a class, queue up
801    // the deferred function body for emission.  These are not seen as
802    // top-level declarations.
803    if (FD->isThisDeclarationADefinition() && MayDeferGeneration(FD))
804      DeferredDeclsToEmit.push_back(D);
805    // A called constructor which has no definition or declaration need be
806    // synthesized.
807    else if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
808      if (CD->isImplicit()) {
809        assert(CD->isUsed() && "Sema doesn't consider constructor as used.");
810        DeferredDeclsToEmit.push_back(D);
811      }
812    } else if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD)) {
813      if (DD->isImplicit()) {
814        assert(DD->isUsed() && "Sema doesn't consider destructor as used.");
815        DeferredDeclsToEmit.push_back(D);
816      }
817    } else if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
818      if (MD->isCopyAssignment() && MD->isImplicit()) {
819        assert(MD->isUsed() && "Sema doesn't consider CopyAssignment as used.");
820        DeferredDeclsToEmit.push_back(D);
821      }
822    }
823  }
824
825  return F;
826}
827
828/// GetAddrOfFunction - Return the address of the given function.  If Ty is
829/// non-null, then this function will use the specified type if it has to
830/// create it (this occurs when we see a definition of the function).
831llvm::Constant *CodeGenModule::GetAddrOfFunction(GlobalDecl GD,
832                                                 const llvm::Type *Ty) {
833  // If there was no specific requested type, just convert it now.
834  if (!Ty)
835    Ty = getTypes().ConvertType(cast<ValueDecl>(GD.getDecl())->getType());
836  MangleBuffer MangledName;
837  getMangledName(MangledName, GD);
838  return GetOrCreateLLVMFunction(MangledName, Ty, GD);
839}
840
841/// CreateRuntimeFunction - Create a new runtime function with the specified
842/// type and name.
843llvm::Constant *
844CodeGenModule::CreateRuntimeFunction(const llvm::FunctionType *FTy,
845                                     llvm::StringRef Name) {
846  return GetOrCreateLLVMFunction(Name, FTy, GlobalDecl());
847}
848
849static bool DeclIsConstantGlobal(ASTContext &Context, const VarDecl *D) {
850  if (!D->getType().isConstant(Context) && !D->getType()->isReferenceType())
851    return false;
852  if (Context.getLangOptions().CPlusPlus &&
853      Context.getBaseElementType(D->getType())->getAs<RecordType>()) {
854    // FIXME: We should do something fancier here!
855    return false;
856  }
857  return true;
858}
859
860/// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
861/// create and return an llvm GlobalVariable with the specified type.  If there
862/// is something in the module with the specified name, return it potentially
863/// bitcasted to the right type.
864///
865/// If D is non-null, it specifies a decl that correspond to this.  This is used
866/// to set the attributes on the global when it is first created.
867llvm::Constant *
868CodeGenModule::GetOrCreateLLVMGlobal(llvm::StringRef MangledName,
869                                     const llvm::PointerType *Ty,
870                                     const VarDecl *D) {
871  // Lookup the entry, lazily creating it if necessary.
872  llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
873  if (Entry) {
874    if (WeakRefReferences.count(Entry)) {
875      if (D && !D->hasAttr<WeakAttr>())
876	Entry->setLinkage(llvm::Function::ExternalLinkage);
877
878      WeakRefReferences.erase(Entry);
879    }
880
881    if (Entry->getType() == Ty)
882      return Entry;
883
884    // Make sure the result is of the correct type.
885    return llvm::ConstantExpr::getBitCast(Entry, Ty);
886  }
887
888  // This is the first use or definition of a mangled name.  If there is a
889  // deferred decl with this name, remember that we need to emit it at the end
890  // of the file.
891  llvm::StringMap<GlobalDecl>::iterator DDI = DeferredDecls.find(MangledName);
892  if (DDI != DeferredDecls.end()) {
893    // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
894    // list, and remove it from DeferredDecls (since we don't need it anymore).
895    DeferredDeclsToEmit.push_back(DDI->second);
896    DeferredDecls.erase(DDI);
897  }
898
899  llvm::GlobalVariable *GV =
900    new llvm::GlobalVariable(getModule(), Ty->getElementType(), false,
901                             llvm::GlobalValue::ExternalLinkage,
902                             0, MangledName, 0,
903                             false, Ty->getAddressSpace());
904
905  // Handle things which are present even on external declarations.
906  if (D) {
907    // FIXME: This code is overly simple and should be merged with other global
908    // handling.
909    GV->setConstant(DeclIsConstantGlobal(Context, D));
910
911    // FIXME: Merge with other attribute handling code.
912    if (D->getStorageClass() == VarDecl::PrivateExtern)
913      GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
914
915    if (D->hasAttr<WeakAttr>() ||
916        D->hasAttr<WeakImportAttr>())
917      GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
918
919    GV->setThreadLocal(D->isThreadSpecified());
920  }
921
922  return GV;
923}
924
925
926/// GetAddrOfGlobalVar - Return the llvm::Constant for the address of the
927/// given global variable.  If Ty is non-null and if the global doesn't exist,
928/// then it will be greated with the specified type instead of whatever the
929/// normal requested type would be.
930llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D,
931                                                  const llvm::Type *Ty) {
932  assert(D->hasGlobalStorage() && "Not a global variable");
933  QualType ASTTy = D->getType();
934  if (Ty == 0)
935    Ty = getTypes().ConvertTypeForMem(ASTTy);
936
937  const llvm::PointerType *PTy =
938    llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
939
940  MangleBuffer MangledName;
941  getMangledName(MangledName, D);
942  return GetOrCreateLLVMGlobal(MangledName, PTy, D);
943}
944
945/// CreateRuntimeVariable - Create a new runtime global variable with the
946/// specified type and name.
947llvm::Constant *
948CodeGenModule::CreateRuntimeVariable(const llvm::Type *Ty,
949                                     llvm::StringRef Name) {
950  return GetOrCreateLLVMGlobal(Name, llvm::PointerType::getUnqual(Ty), 0);
951}
952
953void CodeGenModule::EmitTentativeDefinition(const VarDecl *D) {
954  assert(!D->getInit() && "Cannot emit definite definitions here!");
955
956  if (MayDeferGeneration(D)) {
957    // If we have not seen a reference to this variable yet, place it
958    // into the deferred declarations table to be emitted if needed
959    // later.
960    MangleBuffer MangledName;
961    getMangledName(MangledName, D);
962    if (!GetGlobalValue(MangledName)) {
963      DeferredDecls[MangledName] = D;
964      return;
965    }
966  }
967
968  // The tentative definition is the only definition.
969  EmitGlobalVarDefinition(D);
970}
971
972llvm::GlobalVariable::LinkageTypes
973CodeGenModule::getVtableLinkage(const CXXRecordDecl *RD) {
974  if (RD->isInAnonymousNamespace() || !RD->hasLinkage())
975    return llvm::GlobalVariable::InternalLinkage;
976
977  if (const CXXMethodDecl *KeyFunction
978                                    = RD->getASTContext().getKeyFunction(RD)) {
979    // If this class has a key function, use that to determine the linkage of
980    // the vtable.
981    const FunctionDecl *Def = 0;
982    if (KeyFunction->getBody(Def))
983      KeyFunction = cast<CXXMethodDecl>(Def);
984
985    switch (KeyFunction->getTemplateSpecializationKind()) {
986      case TSK_Undeclared:
987      case TSK_ExplicitSpecialization:
988        if (KeyFunction->isInlined())
989          return llvm::GlobalVariable::WeakODRLinkage;
990
991        return llvm::GlobalVariable::ExternalLinkage;
992
993      case TSK_ImplicitInstantiation:
994      case TSK_ExplicitInstantiationDefinition:
995        return llvm::GlobalVariable::WeakODRLinkage;
996
997      case TSK_ExplicitInstantiationDeclaration:
998        // FIXME: Use available_externally linkage. However, this currently
999        // breaks LLVM's build due to undefined symbols.
1000        //      return llvm::GlobalVariable::AvailableExternallyLinkage;
1001        return llvm::GlobalVariable::WeakODRLinkage;
1002    }
1003  }
1004
1005  switch (RD->getTemplateSpecializationKind()) {
1006  case TSK_Undeclared:
1007  case TSK_ExplicitSpecialization:
1008  case TSK_ImplicitInstantiation:
1009  case TSK_ExplicitInstantiationDefinition:
1010    return llvm::GlobalVariable::WeakODRLinkage;
1011
1012  case TSK_ExplicitInstantiationDeclaration:
1013    // FIXME: Use available_externally linkage. However, this currently
1014    // breaks LLVM's build due to undefined symbols.
1015    //   return llvm::GlobalVariable::AvailableExternallyLinkage;
1016    return llvm::GlobalVariable::WeakODRLinkage;
1017  }
1018
1019  // Silence GCC warning.
1020  return llvm::GlobalVariable::WeakODRLinkage;
1021}
1022
1023static CodeGenModule::GVALinkage
1024GetLinkageForVariable(ASTContext &Context, const VarDecl *VD) {
1025  // If this is a static data member, compute the kind of template
1026  // specialization. Otherwise, this variable is not part of a
1027  // template.
1028  TemplateSpecializationKind TSK = TSK_Undeclared;
1029  if (VD->isStaticDataMember())
1030    TSK = VD->getTemplateSpecializationKind();
1031
1032  Linkage L = VD->getLinkage();
1033  if (L == ExternalLinkage && Context.getLangOptions().CPlusPlus &&
1034      VD->getType()->getLinkage() == UniqueExternalLinkage)
1035    L = UniqueExternalLinkage;
1036
1037  switch (L) {
1038  case NoLinkage:
1039  case InternalLinkage:
1040  case UniqueExternalLinkage:
1041    return CodeGenModule::GVA_Internal;
1042
1043  case ExternalLinkage:
1044    switch (TSK) {
1045    case TSK_Undeclared:
1046    case TSK_ExplicitSpecialization:
1047      return CodeGenModule::GVA_StrongExternal;
1048
1049    case TSK_ExplicitInstantiationDeclaration:
1050      llvm_unreachable("Variable should not be instantiated");
1051      // Fall through to treat this like any other instantiation.
1052
1053    case TSK_ExplicitInstantiationDefinition:
1054      return CodeGenModule::GVA_ExplicitTemplateInstantiation;
1055
1056    case TSK_ImplicitInstantiation:
1057      return CodeGenModule::GVA_TemplateInstantiation;
1058    }
1059  }
1060
1061  return CodeGenModule::GVA_StrongExternal;
1062}
1063
1064CharUnits CodeGenModule::GetTargetTypeStoreSize(const llvm::Type *Ty) const {
1065    return CharUnits::fromQuantity(
1066      TheTargetData.getTypeStoreSizeInBits(Ty) / Context.getCharWidth());
1067}
1068
1069void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
1070  llvm::Constant *Init = 0;
1071  QualType ASTTy = D->getType();
1072  bool NonConstInit = false;
1073
1074  const Expr *InitExpr = D->getAnyInitializer();
1075
1076  if (!InitExpr) {
1077    // This is a tentative definition; tentative definitions are
1078    // implicitly initialized with { 0 }.
1079    //
1080    // Note that tentative definitions are only emitted at the end of
1081    // a translation unit, so they should never have incomplete
1082    // type. In addition, EmitTentativeDefinition makes sure that we
1083    // never attempt to emit a tentative definition if a real one
1084    // exists. A use may still exists, however, so we still may need
1085    // to do a RAUW.
1086    assert(!ASTTy->isIncompleteType() && "Unexpected incomplete type");
1087    Init = EmitNullConstant(D->getType());
1088  } else {
1089    Init = EmitConstantExpr(InitExpr, D->getType());
1090
1091    if (!Init) {
1092      QualType T = InitExpr->getType();
1093      if (getLangOptions().CPlusPlus) {
1094        EmitCXXGlobalVarDeclInitFunc(D);
1095        Init = EmitNullConstant(T);
1096        NonConstInit = true;
1097      } else {
1098        ErrorUnsupported(D, "static initializer");
1099        Init = llvm::UndefValue::get(getTypes().ConvertType(T));
1100      }
1101    }
1102  }
1103
1104  const llvm::Type* InitType = Init->getType();
1105  llvm::Constant *Entry = GetAddrOfGlobalVar(D, InitType);
1106
1107  // Strip off a bitcast if we got one back.
1108  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
1109    assert(CE->getOpcode() == llvm::Instruction::BitCast ||
1110           // all zero index gep.
1111           CE->getOpcode() == llvm::Instruction::GetElementPtr);
1112    Entry = CE->getOperand(0);
1113  }
1114
1115  // Entry is now either a Function or GlobalVariable.
1116  llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Entry);
1117
1118  // We have a definition after a declaration with the wrong type.
1119  // We must make a new GlobalVariable* and update everything that used OldGV
1120  // (a declaration or tentative definition) with the new GlobalVariable*
1121  // (which will be a definition).
1122  //
1123  // This happens if there is a prototype for a global (e.g.
1124  // "extern int x[];") and then a definition of a different type (e.g.
1125  // "int x[10];"). This also happens when an initializer has a different type
1126  // from the type of the global (this happens with unions).
1127  if (GV == 0 ||
1128      GV->getType()->getElementType() != InitType ||
1129      GV->getType()->getAddressSpace() != ASTTy.getAddressSpace()) {
1130
1131    // Move the old entry aside so that we'll create a new one.
1132    Entry->setName(llvm::StringRef());
1133
1134    // Make a new global with the correct type, this is now guaranteed to work.
1135    GV = cast<llvm::GlobalVariable>(GetAddrOfGlobalVar(D, InitType));
1136
1137    // Replace all uses of the old global with the new global
1138    llvm::Constant *NewPtrForOldDecl =
1139        llvm::ConstantExpr::getBitCast(GV, Entry->getType());
1140    Entry->replaceAllUsesWith(NewPtrForOldDecl);
1141
1142    // Erase the old global, since it is no longer used.
1143    cast<llvm::GlobalValue>(Entry)->eraseFromParent();
1144  }
1145
1146  if (const AnnotateAttr *AA = D->getAttr<AnnotateAttr>()) {
1147    SourceManager &SM = Context.getSourceManager();
1148    AddAnnotation(EmitAnnotateAttr(GV, AA,
1149                              SM.getInstantiationLineNumber(D->getLocation())));
1150  }
1151
1152  GV->setInitializer(Init);
1153
1154  // If it is safe to mark the global 'constant', do so now.
1155  GV->setConstant(false);
1156  if (!NonConstInit && DeclIsConstantGlobal(Context, D))
1157    GV->setConstant(true);
1158
1159  GV->setAlignment(getContext().getDeclAlign(D).getQuantity());
1160
1161  // Set the llvm linkage type as appropriate.
1162  GVALinkage Linkage = GetLinkageForVariable(getContext(), D);
1163  if (Linkage == GVA_Internal)
1164    GV->setLinkage(llvm::Function::InternalLinkage);
1165  else if (D->hasAttr<DLLImportAttr>())
1166    GV->setLinkage(llvm::Function::DLLImportLinkage);
1167  else if (D->hasAttr<DLLExportAttr>())
1168    GV->setLinkage(llvm::Function::DLLExportLinkage);
1169  else if (D->hasAttr<WeakAttr>()) {
1170    if (GV->isConstant())
1171      GV->setLinkage(llvm::GlobalVariable::WeakODRLinkage);
1172    else
1173      GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);
1174  } else if (Linkage == GVA_TemplateInstantiation ||
1175             Linkage == GVA_ExplicitTemplateInstantiation)
1176    // FIXME: It seems like we can provide more specific linkage here
1177    // (LinkOnceODR, WeakODR).
1178    GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);
1179  else if (!getLangOptions().CPlusPlus && !CodeGenOpts.NoCommon &&
1180           !D->hasExternalStorage() && !D->getInit() &&
1181           !D->getAttr<SectionAttr>()) {
1182    GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
1183    // common vars aren't constant even if declared const.
1184    GV->setConstant(false);
1185  } else
1186    GV->setLinkage(llvm::GlobalVariable::ExternalLinkage);
1187
1188  SetCommonAttributes(D, GV);
1189
1190  // Emit global variable debug information.
1191  if (CGDebugInfo *DI = getDebugInfo()) {
1192    DI->setLocation(D->getLocation());
1193    DI->EmitGlobalVariable(GV, D);
1194  }
1195}
1196
1197/// ReplaceUsesOfNonProtoTypeWithRealFunction - This function is called when we
1198/// implement a function with no prototype, e.g. "int foo() {}".  If there are
1199/// existing call uses of the old function in the module, this adjusts them to
1200/// call the new function directly.
1201///
1202/// This is not just a cleanup: the always_inline pass requires direct calls to
1203/// functions to be able to inline them.  If there is a bitcast in the way, it
1204/// won't inline them.  Instcombine normally deletes these calls, but it isn't
1205/// run at -O0.
1206static void ReplaceUsesOfNonProtoTypeWithRealFunction(llvm::GlobalValue *Old,
1207                                                      llvm::Function *NewFn) {
1208  // If we're redefining a global as a function, don't transform it.
1209  llvm::Function *OldFn = dyn_cast<llvm::Function>(Old);
1210  if (OldFn == 0) return;
1211
1212  const llvm::Type *NewRetTy = NewFn->getReturnType();
1213  llvm::SmallVector<llvm::Value*, 4> ArgList;
1214
1215  for (llvm::Value::use_iterator UI = OldFn->use_begin(), E = OldFn->use_end();
1216       UI != E; ) {
1217    // TODO: Do invokes ever occur in C code?  If so, we should handle them too.
1218    unsigned OpNo = UI.getOperandNo();
1219    llvm::CallInst *CI = dyn_cast<llvm::CallInst>(*UI++);
1220    if (!CI || OpNo != 0) continue;
1221
1222    // If the return types don't match exactly, and if the call isn't dead, then
1223    // we can't transform this call.
1224    if (CI->getType() != NewRetTy && !CI->use_empty())
1225      continue;
1226
1227    // If the function was passed too few arguments, don't transform.  If extra
1228    // arguments were passed, we silently drop them.  If any of the types
1229    // mismatch, we don't transform.
1230    unsigned ArgNo = 0;
1231    bool DontTransform = false;
1232    for (llvm::Function::arg_iterator AI = NewFn->arg_begin(),
1233         E = NewFn->arg_end(); AI != E; ++AI, ++ArgNo) {
1234      if (CI->getNumOperands()-1 == ArgNo ||
1235          CI->getOperand(ArgNo+1)->getType() != AI->getType()) {
1236        DontTransform = true;
1237        break;
1238      }
1239    }
1240    if (DontTransform)
1241      continue;
1242
1243    // Okay, we can transform this.  Create the new call instruction and copy
1244    // over the required information.
1245    ArgList.append(CI->op_begin()+1, CI->op_begin()+1+ArgNo);
1246    llvm::CallInst *NewCall = llvm::CallInst::Create(NewFn, ArgList.begin(),
1247                                                     ArgList.end(), "", CI);
1248    ArgList.clear();
1249    if (!NewCall->getType()->isVoidTy())
1250      NewCall->takeName(CI);
1251    NewCall->setAttributes(CI->getAttributes());
1252    NewCall->setCallingConv(CI->getCallingConv());
1253
1254    // Finally, remove the old call, replacing any uses with the new one.
1255    if (!CI->use_empty())
1256      CI->replaceAllUsesWith(NewCall);
1257
1258    // Copy any custom metadata attached with CI.
1259    if (llvm::MDNode *DbgNode = CI->getMetadata("dbg"))
1260      NewCall->setMetadata("dbg", DbgNode);
1261    CI->eraseFromParent();
1262  }
1263}
1264
1265
1266void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD) {
1267  const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
1268  const llvm::FunctionType *Ty = getTypes().GetFunctionType(GD);
1269  getMangleContext().mangleInitDiscriminator();
1270  // Get or create the prototype for the function.
1271  llvm::Constant *Entry = GetAddrOfFunction(GD, Ty);
1272
1273  // Strip off a bitcast if we got one back.
1274  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
1275    assert(CE->getOpcode() == llvm::Instruction::BitCast);
1276    Entry = CE->getOperand(0);
1277  }
1278
1279
1280  if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != Ty) {
1281    llvm::GlobalValue *OldFn = cast<llvm::GlobalValue>(Entry);
1282
1283    // If the types mismatch then we have to rewrite the definition.
1284    assert(OldFn->isDeclaration() &&
1285           "Shouldn't replace non-declaration");
1286
1287    // F is the Function* for the one with the wrong type, we must make a new
1288    // Function* and update everything that used F (a declaration) with the new
1289    // Function* (which will be a definition).
1290    //
1291    // This happens if there is a prototype for a function
1292    // (e.g. "int f()") and then a definition of a different type
1293    // (e.g. "int f(int x)").  Move the old function aside so that it
1294    // doesn't interfere with GetAddrOfFunction.
1295    OldFn->setName(llvm::StringRef());
1296    llvm::Function *NewFn = cast<llvm::Function>(GetAddrOfFunction(GD, Ty));
1297
1298    // If this is an implementation of a function without a prototype, try to
1299    // replace any existing uses of the function (which may be calls) with uses
1300    // of the new function
1301    if (D->getType()->isFunctionNoProtoType()) {
1302      ReplaceUsesOfNonProtoTypeWithRealFunction(OldFn, NewFn);
1303      OldFn->removeDeadConstantUsers();
1304    }
1305
1306    // Replace uses of F with the Function we will endow with a body.
1307    if (!Entry->use_empty()) {
1308      llvm::Constant *NewPtrForOldDecl =
1309        llvm::ConstantExpr::getBitCast(NewFn, Entry->getType());
1310      Entry->replaceAllUsesWith(NewPtrForOldDecl);
1311    }
1312
1313    // Ok, delete the old function now, which is dead.
1314    OldFn->eraseFromParent();
1315
1316    Entry = NewFn;
1317  }
1318
1319  llvm::Function *Fn = cast<llvm::Function>(Entry);
1320
1321  CodeGenFunction(*this).GenerateCode(D, Fn);
1322
1323  SetFunctionDefinitionAttributes(D, Fn);
1324  SetLLVMFunctionAttributesForDefinition(D, Fn);
1325
1326  if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>())
1327    AddGlobalCtor(Fn, CA->getPriority());
1328  if (const DestructorAttr *DA = D->getAttr<DestructorAttr>())
1329    AddGlobalDtor(Fn, DA->getPriority());
1330}
1331
1332void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
1333  const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
1334  const AliasAttr *AA = D->getAttr<AliasAttr>();
1335  assert(AA && "Not an alias?");
1336
1337  MangleBuffer MangledName;
1338  getMangledName(MangledName, GD);
1339
1340  // If there is a definition in the module, then it wins over the alias.
1341  // This is dubious, but allow it to be safe.  Just ignore the alias.
1342  llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
1343  if (Entry && !Entry->isDeclaration())
1344    return;
1345
1346  const llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
1347
1348  // Create a reference to the named value.  This ensures that it is emitted
1349  // if a deferred decl.
1350  llvm::Constant *Aliasee;
1351  if (isa<llvm::FunctionType>(DeclTy))
1352    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl());
1353  else
1354    Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
1355                                    llvm::PointerType::getUnqual(DeclTy), 0);
1356
1357  // Create the new alias itself, but don't set a name yet.
1358  llvm::GlobalValue *GA =
1359    new llvm::GlobalAlias(Aliasee->getType(),
1360                          llvm::Function::ExternalLinkage,
1361                          "", Aliasee, &getModule());
1362
1363  if (Entry) {
1364    assert(Entry->isDeclaration());
1365
1366    // If there is a declaration in the module, then we had an extern followed
1367    // by the alias, as in:
1368    //   extern int test6();
1369    //   ...
1370    //   int test6() __attribute__((alias("test7")));
1371    //
1372    // Remove it and replace uses of it with the alias.
1373    GA->takeName(Entry);
1374
1375    Entry->replaceAllUsesWith(llvm::ConstantExpr::getBitCast(GA,
1376                                                          Entry->getType()));
1377    Entry->eraseFromParent();
1378  } else {
1379    GA->setName(MangledName.getString());
1380  }
1381
1382  // Set attributes which are particular to an alias; this is a
1383  // specialization of the attributes which may be set on a global
1384  // variable/function.
1385  if (D->hasAttr<DLLExportAttr>()) {
1386    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
1387      // The dllexport attribute is ignored for undefined symbols.
1388      if (FD->getBody())
1389        GA->setLinkage(llvm::Function::DLLExportLinkage);
1390    } else {
1391      GA->setLinkage(llvm::Function::DLLExportLinkage);
1392    }
1393  } else if (D->hasAttr<WeakAttr>() ||
1394             D->hasAttr<WeakRefAttr>() ||
1395             D->hasAttr<WeakImportAttr>()) {
1396    GA->setLinkage(llvm::Function::WeakAnyLinkage);
1397  }
1398
1399  SetCommonAttributes(D, GA);
1400}
1401
1402/// getBuiltinLibFunction - Given a builtin id for a function like
1403/// "__builtin_fabsf", return a Function* for "fabsf".
1404llvm::Value *CodeGenModule::getBuiltinLibFunction(const FunctionDecl *FD,
1405                                                  unsigned BuiltinID) {
1406  assert((Context.BuiltinInfo.isLibFunction(BuiltinID) ||
1407          Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) &&
1408         "isn't a lib fn");
1409
1410  // Get the name, skip over the __builtin_ prefix (if necessary).
1411  const char *Name = Context.BuiltinInfo.GetName(BuiltinID);
1412  if (Context.BuiltinInfo.isLibFunction(BuiltinID))
1413    Name += 10;
1414
1415  const llvm::FunctionType *Ty =
1416    cast<llvm::FunctionType>(getTypes().ConvertType(FD->getType()));
1417
1418  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl(FD));
1419}
1420
1421llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
1422                                            unsigned NumTys) {
1423  return llvm::Intrinsic::getDeclaration(&getModule(),
1424                                         (llvm::Intrinsic::ID)IID, Tys, NumTys);
1425}
1426
1427llvm::Function *CodeGenModule::getMemCpyFn() {
1428  if (MemCpyFn) return MemCpyFn;
1429  const llvm::Type *IntPtr = TheTargetData.getIntPtrType(VMContext);
1430  return MemCpyFn = getIntrinsic(llvm::Intrinsic::memcpy, &IntPtr, 1);
1431}
1432
1433llvm::Function *CodeGenModule::getMemMoveFn() {
1434  if (MemMoveFn) return MemMoveFn;
1435  const llvm::Type *IntPtr = TheTargetData.getIntPtrType(VMContext);
1436  return MemMoveFn = getIntrinsic(llvm::Intrinsic::memmove, &IntPtr, 1);
1437}
1438
1439llvm::Function *CodeGenModule::getMemSetFn() {
1440  if (MemSetFn) return MemSetFn;
1441  const llvm::Type *IntPtr = TheTargetData.getIntPtrType(VMContext);
1442  return MemSetFn = getIntrinsic(llvm::Intrinsic::memset, &IntPtr, 1);
1443}
1444
1445static llvm::StringMapEntry<llvm::Constant*> &
1446GetConstantCFStringEntry(llvm::StringMap<llvm::Constant*> &Map,
1447                         const StringLiteral *Literal,
1448                         bool TargetIsLSB,
1449                         bool &IsUTF16,
1450                         unsigned &StringLength) {
1451  unsigned NumBytes = Literal->getByteLength();
1452
1453  // Check for simple case.
1454  if (!Literal->containsNonAsciiOrNull()) {
1455    StringLength = NumBytes;
1456    return Map.GetOrCreateValue(llvm::StringRef(Literal->getStrData(),
1457                                                StringLength));
1458  }
1459
1460  // Otherwise, convert the UTF8 literals into a byte string.
1461  llvm::SmallVector<UTF16, 128> ToBuf(NumBytes);
1462  const UTF8 *FromPtr = (UTF8 *)Literal->getStrData();
1463  UTF16 *ToPtr = &ToBuf[0];
1464
1465  ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1466                                               &ToPtr, ToPtr + NumBytes,
1467                                               strictConversion);
1468
1469  // Check for conversion failure.
1470  if (Result != conversionOK) {
1471    // FIXME: Have Sema::CheckObjCString() validate the UTF-8 string and remove
1472    // this duplicate code.
1473    assert(Result == sourceIllegal && "UTF-8 to UTF-16 conversion failed");
1474    StringLength = NumBytes;
1475    return Map.GetOrCreateValue(llvm::StringRef(Literal->getStrData(),
1476                                                StringLength));
1477  }
1478
1479  // ConvertUTF8toUTF16 returns the length in ToPtr.
1480  StringLength = ToPtr - &ToBuf[0];
1481
1482  // Render the UTF-16 string into a byte array and convert to the target byte
1483  // order.
1484  //
1485  // FIXME: This isn't something we should need to do here.
1486  llvm::SmallString<128> AsBytes;
1487  AsBytes.reserve(StringLength * 2);
1488  for (unsigned i = 0; i != StringLength; ++i) {
1489    unsigned short Val = ToBuf[i];
1490    if (TargetIsLSB) {
1491      AsBytes.push_back(Val & 0xFF);
1492      AsBytes.push_back(Val >> 8);
1493    } else {
1494      AsBytes.push_back(Val >> 8);
1495      AsBytes.push_back(Val & 0xFF);
1496    }
1497  }
1498  // Append one extra null character, the second is automatically added by our
1499  // caller.
1500  AsBytes.push_back(0);
1501
1502  IsUTF16 = true;
1503  return Map.GetOrCreateValue(llvm::StringRef(AsBytes.data(), AsBytes.size()));
1504}
1505
1506llvm::Constant *
1507CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
1508  unsigned StringLength = 0;
1509  bool isUTF16 = false;
1510  llvm::StringMapEntry<llvm::Constant*> &Entry =
1511    GetConstantCFStringEntry(CFConstantStringMap, Literal,
1512                             getTargetData().isLittleEndian(),
1513                             isUTF16, StringLength);
1514
1515  if (llvm::Constant *C = Entry.getValue())
1516    return C;
1517
1518  llvm::Constant *Zero =
1519      llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext));
1520  llvm::Constant *Zeros[] = { Zero, Zero };
1521
1522  // If we don't already have it, get __CFConstantStringClassReference.
1523  if (!CFConstantStringClassRef) {
1524    const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
1525    Ty = llvm::ArrayType::get(Ty, 0);
1526    llvm::Constant *GV = CreateRuntimeVariable(Ty,
1527                                           "__CFConstantStringClassReference");
1528    // Decay array -> ptr
1529    CFConstantStringClassRef =
1530      llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
1531  }
1532
1533  QualType CFTy = getContext().getCFConstantStringType();
1534
1535  const llvm::StructType *STy =
1536    cast<llvm::StructType>(getTypes().ConvertType(CFTy));
1537
1538  std::vector<llvm::Constant*> Fields(4);
1539
1540  // Class pointer.
1541  Fields[0] = CFConstantStringClassRef;
1542
1543  // Flags.
1544  const llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
1545  Fields[1] = isUTF16 ? llvm::ConstantInt::get(Ty, 0x07d0) :
1546    llvm::ConstantInt::get(Ty, 0x07C8);
1547
1548  // String pointer.
1549  llvm::Constant *C = llvm::ConstantArray::get(VMContext, Entry.getKey().str());
1550
1551  llvm::GlobalValue::LinkageTypes Linkage;
1552  bool isConstant;
1553  if (isUTF16) {
1554    // FIXME: why do utf strings get "_" labels instead of "L" labels?
1555    Linkage = llvm::GlobalValue::InternalLinkage;
1556    // Note: -fwritable-strings doesn't make unicode CFStrings writable, but
1557    // does make plain ascii ones writable.
1558    isConstant = true;
1559  } else {
1560    Linkage = llvm::GlobalValue::PrivateLinkage;
1561    isConstant = !Features.WritableStrings;
1562  }
1563
1564  llvm::GlobalVariable *GV =
1565    new llvm::GlobalVariable(getModule(), C->getType(), isConstant, Linkage, C,
1566                             ".str");
1567  if (isUTF16) {
1568    CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy);
1569    GV->setAlignment(Align.getQuantity());
1570  }
1571  Fields[2] = llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
1572
1573  // String length.
1574  Ty = getTypes().ConvertType(getContext().LongTy);
1575  Fields[3] = llvm::ConstantInt::get(Ty, StringLength);
1576
1577  // The struct.
1578  C = llvm::ConstantStruct::get(STy, Fields);
1579  GV = new llvm::GlobalVariable(getModule(), C->getType(), true,
1580                                llvm::GlobalVariable::PrivateLinkage, C,
1581                                "_unnamed_cfstring_");
1582  if (const char *Sect = getContext().Target.getCFStringSection())
1583    GV->setSection(Sect);
1584  Entry.setValue(GV);
1585
1586  return GV;
1587}
1588
1589/// GetStringForStringLiteral - Return the appropriate bytes for a
1590/// string literal, properly padded to match the literal type.
1591std::string CodeGenModule::GetStringForStringLiteral(const StringLiteral *E) {
1592  const char *StrData = E->getStrData();
1593  unsigned Len = E->getByteLength();
1594
1595  const ConstantArrayType *CAT =
1596    getContext().getAsConstantArrayType(E->getType());
1597  assert(CAT && "String isn't pointer or array!");
1598
1599  // Resize the string to the right size.
1600  std::string Str(StrData, StrData+Len);
1601  uint64_t RealLen = CAT->getSize().getZExtValue();
1602
1603  if (E->isWide())
1604    RealLen *= getContext().Target.getWCharWidth()/8;
1605
1606  Str.resize(RealLen, '\0');
1607
1608  return Str;
1609}
1610
1611/// GetAddrOfConstantStringFromLiteral - Return a pointer to a
1612/// constant array for the given string literal.
1613llvm::Constant *
1614CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
1615  // FIXME: This can be more efficient.
1616  // FIXME: We shouldn't need to bitcast the constant in the wide string case.
1617  llvm::Constant *C = GetAddrOfConstantString(GetStringForStringLiteral(S));
1618  if (S->isWide()) {
1619    llvm::Type *DestTy =
1620        llvm::PointerType::getUnqual(getTypes().ConvertType(S->getType()));
1621    C = llvm::ConstantExpr::getBitCast(C, DestTy);
1622  }
1623  return C;
1624}
1625
1626/// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
1627/// array for the given ObjCEncodeExpr node.
1628llvm::Constant *
1629CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
1630  std::string Str;
1631  getContext().getObjCEncodingForType(E->getEncodedType(), Str);
1632
1633  return GetAddrOfConstantCString(Str);
1634}
1635
1636
1637/// GenerateWritableString -- Creates storage for a string literal.
1638static llvm::Constant *GenerateStringLiteral(const std::string &str,
1639                                             bool constant,
1640                                             CodeGenModule &CGM,
1641                                             const char *GlobalName) {
1642  // Create Constant for this string literal. Don't add a '\0'.
1643  llvm::Constant *C =
1644      llvm::ConstantArray::get(CGM.getLLVMContext(), str, false);
1645
1646  // Create a global variable for this string
1647  return new llvm::GlobalVariable(CGM.getModule(), C->getType(), constant,
1648                                  llvm::GlobalValue::PrivateLinkage,
1649                                  C, GlobalName);
1650}
1651
1652/// GetAddrOfConstantString - Returns a pointer to a character array
1653/// containing the literal. This contents are exactly that of the
1654/// given string, i.e. it will not be null terminated automatically;
1655/// see GetAddrOfConstantCString. Note that whether the result is
1656/// actually a pointer to an LLVM constant depends on
1657/// Feature.WriteableStrings.
1658///
1659/// The result has pointer to array type.
1660llvm::Constant *CodeGenModule::GetAddrOfConstantString(const std::string &str,
1661                                                       const char *GlobalName) {
1662  bool IsConstant = !Features.WritableStrings;
1663
1664  // Get the default prefix if a name wasn't specified.
1665  if (!GlobalName)
1666    GlobalName = ".str";
1667
1668  // Don't share any string literals if strings aren't constant.
1669  if (!IsConstant)
1670    return GenerateStringLiteral(str, false, *this, GlobalName);
1671
1672  llvm::StringMapEntry<llvm::Constant *> &Entry =
1673    ConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
1674
1675  if (Entry.getValue())
1676    return Entry.getValue();
1677
1678  // Create a global variable for this.
1679  llvm::Constant *C = GenerateStringLiteral(str, true, *this, GlobalName);
1680  Entry.setValue(C);
1681  return C;
1682}
1683
1684/// GetAddrOfConstantCString - Returns a pointer to a character
1685/// array containing the literal and a terminating '\-'
1686/// character. The result has pointer to array type.
1687llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &str,
1688                                                        const char *GlobalName){
1689  return GetAddrOfConstantString(str + '\0', GlobalName);
1690}
1691
1692/// EmitObjCPropertyImplementations - Emit information for synthesized
1693/// properties for an implementation.
1694void CodeGenModule::EmitObjCPropertyImplementations(const
1695                                                    ObjCImplementationDecl *D) {
1696  for (ObjCImplementationDecl::propimpl_iterator
1697         i = D->propimpl_begin(), e = D->propimpl_end(); i != e; ++i) {
1698    ObjCPropertyImplDecl *PID = *i;
1699
1700    // Dynamic is just for type-checking.
1701    if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
1702      ObjCPropertyDecl *PD = PID->getPropertyDecl();
1703
1704      // Determine which methods need to be implemented, some may have
1705      // been overridden. Note that ::isSynthesized is not the method
1706      // we want, that just indicates if the decl came from a
1707      // property. What we want to know is if the method is defined in
1708      // this implementation.
1709      if (!D->getInstanceMethod(PD->getGetterName()))
1710        CodeGenFunction(*this).GenerateObjCGetter(
1711                                 const_cast<ObjCImplementationDecl *>(D), PID);
1712      if (!PD->isReadOnly() &&
1713          !D->getInstanceMethod(PD->getSetterName()))
1714        CodeGenFunction(*this).GenerateObjCSetter(
1715                                 const_cast<ObjCImplementationDecl *>(D), PID);
1716    }
1717  }
1718}
1719
1720/// EmitNamespace - Emit all declarations in a namespace.
1721void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
1722  for (RecordDecl::decl_iterator I = ND->decls_begin(), E = ND->decls_end();
1723       I != E; ++I)
1724    EmitTopLevelDecl(*I);
1725}
1726
1727// EmitLinkageSpec - Emit all declarations in a linkage spec.
1728void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
1729  if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
1730      LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
1731    ErrorUnsupported(LSD, "linkage spec");
1732    return;
1733  }
1734
1735  for (RecordDecl::decl_iterator I = LSD->decls_begin(), E = LSD->decls_end();
1736       I != E; ++I)
1737    EmitTopLevelDecl(*I);
1738}
1739
1740/// EmitTopLevelDecl - Emit code for a single top level declaration.
1741void CodeGenModule::EmitTopLevelDecl(Decl *D) {
1742  // If an error has occurred, stop code generation, but continue
1743  // parsing and semantic analysis (to ensure all warnings and errors
1744  // are emitted).
1745  if (Diags.hasErrorOccurred())
1746    return;
1747
1748  // Ignore dependent declarations.
1749  if (D->getDeclContext() && D->getDeclContext()->isDependentContext())
1750    return;
1751
1752  switch (D->getKind()) {
1753  case Decl::CXXConversion:
1754  case Decl::CXXMethod:
1755  case Decl::Function:
1756    // Skip function templates
1757    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate())
1758      return;
1759
1760    EmitGlobal(cast<FunctionDecl>(D));
1761    break;
1762
1763  case Decl::Var:
1764    EmitGlobal(cast<VarDecl>(D));
1765    break;
1766
1767  // C++ Decls
1768  case Decl::Namespace:
1769    EmitNamespace(cast<NamespaceDecl>(D));
1770    break;
1771    // No code generation needed.
1772  case Decl::UsingShadow:
1773  case Decl::Using:
1774  case Decl::UsingDirective:
1775  case Decl::ClassTemplate:
1776  case Decl::FunctionTemplate:
1777  case Decl::NamespaceAlias:
1778    break;
1779  case Decl::CXXConstructor:
1780    // Skip function templates
1781    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate())
1782      return;
1783
1784    EmitCXXConstructors(cast<CXXConstructorDecl>(D));
1785    break;
1786  case Decl::CXXDestructor:
1787    EmitCXXDestructors(cast<CXXDestructorDecl>(D));
1788    break;
1789
1790  case Decl::StaticAssert:
1791    // Nothing to do.
1792    break;
1793
1794  // Objective-C Decls
1795
1796  // Forward declarations, no (immediate) code generation.
1797  case Decl::ObjCClass:
1798  case Decl::ObjCForwardProtocol:
1799  case Decl::ObjCCategory:
1800  case Decl::ObjCInterface:
1801    break;
1802
1803  case Decl::ObjCProtocol:
1804    Runtime->GenerateProtocol(cast<ObjCProtocolDecl>(D));
1805    break;
1806
1807  case Decl::ObjCCategoryImpl:
1808    // Categories have properties but don't support synthesize so we
1809    // can ignore them here.
1810    Runtime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
1811    break;
1812
1813  case Decl::ObjCImplementation: {
1814    ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
1815    EmitObjCPropertyImplementations(OMD);
1816    Runtime->GenerateClass(OMD);
1817    break;
1818  }
1819  case Decl::ObjCMethod: {
1820    ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
1821    // If this is not a prototype, emit the body.
1822    if (OMD->getBody())
1823      CodeGenFunction(*this).GenerateObjCMethod(OMD);
1824    break;
1825  }
1826  case Decl::ObjCCompatibleAlias:
1827    // compatibility-alias is a directive and has no code gen.
1828    break;
1829
1830  case Decl::LinkageSpec:
1831    EmitLinkageSpec(cast<LinkageSpecDecl>(D));
1832    break;
1833
1834  case Decl::FileScopeAsm: {
1835    FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
1836    llvm::StringRef AsmString = AD->getAsmString()->getString();
1837
1838    const std::string &S = getModule().getModuleInlineAsm();
1839    if (S.empty())
1840      getModule().setModuleInlineAsm(AsmString);
1841    else
1842      getModule().setModuleInlineAsm(S + '\n' + AsmString.str());
1843    break;
1844  }
1845
1846  default:
1847    // Make sure we handled everything we should, every other kind is a
1848    // non-top-level decl.  FIXME: Would be nice to have an isTopLevelDeclKind
1849    // function. Need to recode Decl::Kind to do that easily.
1850    assert(isa<TypeDecl>(D) && "Unsupported decl kind");
1851  }
1852}
1853